Among the most significant ecological discoveries of the past decade stands the Coral Triangle's newly documented reef system. A biodiversity...

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

• Among the most significant ecological discoveries of the past decade
  • stands
    • the Coral Triangle's newly documented reef system.

• A biodiversity hotspot,
• a climate resilience indicator,
• and a crucial habitat for endangered species,
  • ______ [varies by choice]
    • reveals
      • unexpected adaptations to warming ocean temperatures.

Understanding the Meaning

Let's start with the first sentence:

'Among the most significant ecological discoveries of the past decade stands the Coral Triangle's newly documented reef system.'

This sentence has an inverted structure:

• Instead of saying "the reef system stands among the discoveries"
• It flips it to "stands the reef system"
• The main point: this reef system is one of the most important ecological discoveries recently.

Now let's look at the second sentence, which has our blank:

'A biodiversity hotspot, a climate resilience indicator, and a crucial habitat for endangered species, ______'

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

• Choice A introduces "the research team documented findings"
• Choice B introduces "Indonesia's territorial waters contain a reef system"
• Choice C introduces "the reef system, first surveyed in 2019"
• Choice D introduces "first surveyed in 2019, marine biologists discovered a reef system"

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

The sentence continues: 'reveals unexpected adaptations to warming ocean temperatures.'

Now let's understand what the complete sentence is trying to say:

• We have three descriptive phrases at the beginning:
  • 'A biodiversity hotspot'
  • 'a climate resilience indicator'
  • 'and a crucial habitat for endangered species'
• These three phrases are separated by commas and sit before the blank
• After the blank, we have 'reveals unexpected adaptations...'

What do we notice about the structure here?

• Those three opening phrases are describing something - they're giving us three ways to understand what something IS.
• Whatever comes after those phrases should be the thing they're describing.
• Then 'reveals' is the action that thing performs.
• Looking back at the first sentence, the topic is clearly the reef system.

So the structure should be:

• [Three phrases describing the reef system], the reef system [does something]

The pattern is: describing phrases → the thing being described → what it does

So we need: the reef system to come after those three descriptive phrases, and it needs to be the subject of the verb "reveals."

Choice C gives us exactly that: "the reef system, first surveyed in 2019,"

The complete sentence means:

• This reef system (which we learned about in the first sentence)
• Can be understood in three ways: it's a biodiversity hotspot, a climate indicator, and a habitat for endangered species
• And it reveals unexpected adaptations to warming ocean temperatures
• It was first surveyed in 2019 (additional detail)

GRAMMAR CONCEPT APPLIED

Introductory Descriptive Phrases Must Describe What Immediately Follows

When you begin a sentence with descriptive phrases separated by commas (called appositives in grammar terms), these phrases must describe the noun that comes right after them. That noun then serves as the subject for the main verb.

The pattern:

• [Descriptive phrase 1, descriptive phrase 2, descriptive phrase 3], [NOUN being described], [verb]...

Example 1:

• ✓ "A talented musician, a dedicated teacher, and a community leader, Sarah transformed the local arts program."
  • The three phrases describe Sarah
  • Sarah is the subject of "transformed"

Example 2:

• ✗ "A talented musician, a dedicated teacher, and a community leader, the program was transformed."
  • The three phrases can't logically describe "the program"
  • Misplaced modification

In this question:

• "A biodiversity hotspot, a climate resilience indicator, and a crucial habitat for endangered species" are three descriptive phrases
• They must describe what comes next: the reef system
• The reef system then serves as the subject of "reveals"
• "First surveyed in 2019" is an additional non-essential modifier about the reef system, properly set off by commas