In the 1970s, Janaki Ammal, a prominent botanist, emerged as a powerful voice in India's environmental conservation movement. Her exhaustive...

Let's begin by understanding the meaning of this sentence. We'll use our understanding of pause points and segment the sentence as shown - understanding and assimilating the meaning of each segment bit by bit!

Sentence Structure

• In the 1970s,
  • Janaki Ammal,
    • a prominent botanist,
  • emerged as a powerful voice in India's environmental conservation movement.

• Her exhaustive chromosomal survey of plants
  • in Silent Valley,
    • a pristine tropical forest in Kerala, India,
      • that is home to nearly 1,000 species of native flora
        • (many of which are endangered),
  • [?] instrumental in the government's decision to preserve the forest.

Understanding the Meaning

The first sentence gives us the context:

• 'In the 1970s, Janaki Ammal, a prominent botanist,'
  • We learn when this happened (1970s) and who the person is
  • Janaki Ammal was a botanist

• 'emerged as a powerful voice in India's environmental conservation movement'
  • She became an important advocate for protecting the environment in India

Now the second sentence tells us specifically what she did:

• 'Her exhaustive chromosomal survey of plants'
  • This is what we're focusing on - a detailed scientific study she conducted
  • She surveyed/studied the chromosomes of plants

This is where we have the blank. Let's look at the choices:

• are / were / have been / was
  • These are all forms of "to be"
  • They differ in whether they're singular or plural, and in tense

To see what works here, let's read the rest of the sentence and understand what it's saying!

• 'in Silent Valley,'
  • tells us where the survey took place

• 'a pristine tropical forest in Kerala, India,'
  • describes what Silent Valley is - an untouched tropical forest in Kerala

• 'that is home to nearly 1,000 species of native flora'
  • tells us about the forest - it has almost 1,000 species of plants that naturally grow there

• '(many of which are endangered)'
  • adds that many of these plant species are in danger of extinction

• '[blank] instrumental in the government's decision to preserve the forest'
  • This is what the sentence is really saying: the survey played a key role
  • It influenced the government to protect this forest

What do we notice about the structure here?

• The subject of this sentence is 'Her exhaustive chromosomal survey'
  • "Survey" is singular - it's one study/survey

• Everything between "survey" and the blank is describing where and what:
  • "of plants" - what she surveyed
  • "in Silent Valley" - where it was
  • "a pristine tropical forest..." - what Silent Valley is
  • "that is home to..." - more about the forest
  • "(many of which are endangered)" - additional detail

• These middle parts contain several plural nouns:
  • plants, species, flora
  • But these aren't the subject - they're just describing details

• The verb needs to agree with "survey" (singular), not with these other nouns

• The time frame is the 1970s, so we need past tense

So we need: was (singular, past tense)

The correct answer is D.

GRAMMAR CONCEPT APPLIED

Matching Verbs to Subjects When They're Separated

When the subject and verb in a sentence are separated by long descriptive phrases, you need to identify the true subject and make sure the verb agrees with it - not with other nouns that happen to appear in between.

The pattern:

• Simple version: The survey was instrumental
  • Subject: "survey" (singular)
  • Verb: "was" (singular, past)

• With intervening modification: The survey of plants in Silent Valley, a pristine tropical forest that is home to nearly 1,000 species of native flora, was instrumental
  • Subject: still "survey" (singular)
  • Intervening phrases: "of plants," "in Silent Valley," "a pristine tropical forest..."
  • These phrases contain plural nouns: plants, species, flora
  • But the verb must still agree with "survey," not with these other nouns
  • Verb: still "was" (singular, past)

How to apply this:

1. Find the true subject - who or what is performing the main action?
   • In this sentence: "Her exhaustive chromosomal survey" is doing something
2. Identify intervening elements - prepositional phrases (starting with "of," "in," "at," etc.) and descriptive clauses
   • These add information but don't change what the subject is
3. Ignore distractor nouns - plural nouns in these phrases might tempt you to use a plural verb
   • "plants," "species," and "flora" are all plural, but they're not the subject
4. Match the verb to the actual subject - in both number and tense
   • "survey" is singular → "was" (not "were")
   • Action occurred in 1970s → past tense

This grammatical relationship (called subject-verb agreement in grammar terms) requires you to look past the surrounding words and connect the verb directly to its true subject.