When marine biologist Sylvia Earle first descended into the Coral Triangle's waters in 1979, she documented unprecedented biodiversity. So extensive...

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

• When marine biologist Sylvia Earle first descended into the Coral Triangle's waters in 1979,
  • she documented unprecedented biodiversity.
• So extensive were her observations of symbiotic relationships between species
  • that her expedition's findings on reef ecosystems
    • [?] marine conservation efforts worldwide.

Understanding the Meaning

Let's start with the first sentence to get the context:

'When marine biologist Sylvia Earle first descended into the Coral Triangle's waters in 1979,
she documented unprecedented biodiversity.'

This tells us:

• In 1979, a marine biologist named Sylvia Earle went diving in the Coral Triangle
• She documented biodiversity that had never been seen before

Now the second sentence:

'So extensive were her observations of symbiotic relationships between species...'

• This is emphasizing just how extensive (thorough, wide-ranging) her observations were
• She was observing symbiotic relationships - how different species interact and depend on each other
• The sentence is using an inverted structure ("So extensive were...") for emphasis

The sentence continues: '...that her expedition's findings on reef ecosystems ______ marine conservation efforts worldwide.'

Now here's where we need to fill in the blank. This is the result of those extensive observations - what did the findings do?

Let's look at our choices:

• A: influences (singular)
• B: influence (plural)
• C: has influenced (singular)
• D: is influencing (singular)

The choices are asking us to decide whether we need a singular or plural verb.

To figure this out, we need to identify what the subject is - what is doing the action?

• The subject is: 'her expedition's findings on reef ecosystems'
  • 'findings' is the core subject
  • 'her expedition's' tells us which findings
  • 'on reef ecosystems' describes what the findings are about

What do we notice about the subject?

• 'Findings' is plural - it means multiple findings or results from the research
• Even though 'on reef ecosystems' comes between 'findings' and the blank, it's just a prepositional phrase describing the findings
• It doesn't change the fact that 'findings' is plural

So we need a plural verb to match the plural subject 'findings.'

The correct answer is B: influence - the only plural verb form among the choices.

GRAMMAR CONCEPT APPLIED

Matching Verbs to Their Subjects When Words Come Between

The verb in a sentence must agree in number (singular or plural) with its subject, even when other words or phrases come between them. Prepositional phrases (phrases starting with words like "of," "on," "in," "with") are especially common separators, but they don't affect agreement.

The pattern:

Find the core subject → Determine if it's singular or plural → Match the verb to that number

Example 1:

• Incorrect: "The results of the experiment shows a clear pattern"
• Correct: "The results of the experiment show a clear pattern"
• Subject: "results" (plural)
• "of the experiment" is a prepositional phrase - ignore it for agreement
• Verb must be plural: "show"

Example 2:

• Incorrect: "The collection of rare stamps are valuable"
• Correct: "The collection of rare stamps is valuable"
• Subject: "collection" (singular)
• "of rare stamps" is a prepositional phrase - ignore it for agreement
• Verb must be singular: "is"

In our question:

• Subject: "findings" (plural)
• Intervening phrase: "on reef ecosystems" (describes the findings but doesn't affect agreement)
• Verb must be plural: "influence"

The phrase "on reef ecosystems" sits right between the subject and verb, which can make you want to match the verb to "ecosystems," but that's not the subject. Always trace back to find what's actually performing the action.