Forming extensive networks via mycorrhizal association-that is, a symbiotic relationship between plants and fungi- ______

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

• Forming extensive networks via mycorrhizal association—
• that is, a symbiotic relationship between plants and fungi—
• (?)

Understanding the Meaning

Let's start reading from the beginning:

'Forming extensive networks via mycorrhizal association—'

• This is describing something that forms (creates) extensive networks
• It does this through mycorrhizal association

'—that is, a symbiotic relationship between plants and fungi—'

• This clarifies what mycorrhizal association means
• It's a symbiotic relationship (a mutually beneficial partnership) between plants and fungi

This is where we have the blank.

Let's look at the choices to see what varies:

• Choice A: "it is the entanglement... that makes nutrient transport possible"
• Choice B: "the transport of nutrients is possible..."
• Choice C: "nutrients can be transported..."
• Choice D: "pine trees and the fungus Tricholoma matsutake can transport nutrients..."

The choices give us different subjects - different actors that could follow this opening phrase.

To see what works here, let's understand what each choice is actually saying and which one makes logical sense!

What do we notice about the structure?

• The opening phrase "Forming extensive networks" is describing something—
  • Whatever comes right after this phrase must be the thing that's doing the forming.
  • This is how these opening descriptive phrases work: they describe the subject that comes next.

Now let's think: what can actually FORM these networks?

• Choice A puts "it is the entanglement..." after the opening phrase
  • But "it" is vague, and entanglement doesn't form networks— it's a description of what the network looks like

• Choice B puts "the transport of nutrients..." after the opening phrase
  • But transport (the movement of nutrients) doesn't form networks— it's what happens through networks

• Choice C puts "nutrients..." after the opening phrase
  • But nutrients don't form networks— they're just what gets moved through the networks

• Choice D puts "pine trees and the fungus Tricholoma matsutake..." after the opening phrase
  • YES! These are the living organisms— the actual plants and fungi that CREATE the mycorrhizal networks
  • Pine trees and the fungus are the ones doing the forming

The correct answer is Choice D because pine trees and the fungus are the organisms that logically form these extensive networks. The opening phrase "Forming extensive networks" needs to describe these organisms, not the results or processes that come from the networks.

GRAMMAR CONCEPT APPLIED

Opening Descriptive Phrases Must Describe What Comes Next

When a sentence begins with a descriptive phrase (called a participial modifier in grammar terms), especially one starting with an -ing verb form, that phrase must logically describe the noun that comes immediately after it.

The Pattern:

• Opening modifier: Working late into the night,
• Must describe → the students finished their project
• "Working late" describes the students (they're the ones working)

• Opening modifier: Having won the championship,
• Must describe → the team celebrated with fans
• "Having won" describes the team (they're the ones who won)

The Error Pattern:

• Opening modifier: Working late into the night,
• Incorrectly describes → the project was completed
• The project didn't work late; the students did

In This Question:

• Opening modifier: Forming extensive networks via mycorrhizal association
• Must describe → pine trees and the fungus Tricholoma matsutake
• These organisms are the ones forming the networks

• Would incorrectly describe → nutrients / transport / entanglement
• None of these can logically "form" networks

The Key Test: Ask yourself, "Can this noun/subject logically do the action described in the opening phrase?" If not, it's a modifier error.