The research team identified three critical factors affecting crop _____ soil nutrient levels, water availability, and pest management practices.

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

• The research team identified three critical factors
• affecting crop yields[?]
• soil nutrient levels,
• water availability, and
• pest management practices.

Understanding the Meaning

The sentence starts by telling us what a research team did:

• 'The research team identified three critical factors'
  • They found three important factors

Then we learn what these factors relate to:

• 'affecting crop yields'
  • These factors have an impact on how much crops produce

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

• A adds a colon (:)
• B adds the word "of"
• C adds an em dash (—)
• D adds "of" followed by a comma

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

The sentence continues with:

• 'soil nutrient levels, water availability, and pest management practices'

Now let's understand what this is telling us:

• This is a list of three things:
  • soil nutrient levels
  • water availability
  • pest management practices
• These three items ARE the "three critical factors" mentioned earlier
  • The sentence first announces "we found three factors"
  • Then it tells us what those three factors are

What do we notice about the structure here?

• The first part is a complete thought:
  • "The research team identified three critical factors affecting crop yields"
  • This could stand alone as a sentence
  • It announces that a list is coming ("three critical factors")
• The second part gives us the actual list
  • The specific three factors that were just announced
• We need punctuation that introduces a list after a complete statement that announces it

So we need a colon (:). The colon is the standard punctuation mark for introducing a list when what comes before is a complete sentence that sets up the list.

The correct answer is A: yields:

GRAMMAR CONCEPT APPLIED

Using Colons to Introduce Lists

When you have a complete sentence that announces or introduces a list, you use a colon before the list begins. The key is that what comes before the colon must be able to stand alone as a complete thought:

Pattern:

• Complete announcement + colon + list of items

Example 1:

• The committee identified three priorities: budget reform, staff training, and community outreach.
• Before colon: "The committee identified three priorities" (complete thought)
• After colon: the three priorities listed

Example 2:

• She needed several supplies for the project: paint, brushes, canvas, and an easel.
• Before colon: "She needed several supplies for the project" (complete thought)
• After colon: the specific supplies listed

In our question:

• "The research team identified three critical factors affecting crop yields" (complete thought announcing the list)
• Colon
• "soil nutrient levels, water availability, and pest management practices" (the three factors)

The colon signals to the reader: "Here comes the specific information I just announced."