In order to prevent nonnative fish species from moving freely between the Mediterranean and Red Seas, marine biologist Bella Galil...

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 order to prevent nonnative fish species
• from moving freely between the Mediterranean and Red Seas,
• marine biologist Bella Galil has proposed
• that a saline lock system be installed
• along the Suez Canal
• in Egypt's Great Bitter Lakes.
• The lock would increase the salinity of the lakes
• and [?] a natural barrier of water
• most marine creatures would be unable to cross.
• Where [?] = creates/create/creating/created

Understanding the Meaning

Let's start reading from the beginning:

'In order to prevent nonnative fish species from moving freely between the Mediterranean and Red Seas'

• This tells us the goal – stopping fish from one sea from traveling to the other sea.

'marine biologist Bella Galil has proposed that a saline lock system be installed along the Suez Canal in Egypt's Great Bitter Lakes.'

• Bella Galil has an idea: install a special lock system in the Great Bitter Lakes (which are part of the Suez Canal).

Now we get to the second sentence, which explains what this lock would do:

'The lock would increase the salinity of the lakes'

• The lock would make the lakes saltier.

'and ______ a natural barrier of water most marine creatures would be unable to cross.'

• This is where we have the blank.
• Let's look at the choices: creates, create, creating, created

To see what works here, let's understand what this part is saying:

• The lock would do two things:
  • First: increase the salinity
  • Second: [blank] a natural barrier

What do we notice about the structure here?

• We have two actions connected by "and":
  • 'would increase the salinity'
  • 'and ______ a natural barrier'
• Both actions share the same helping word "would":
  • The lock would increase... and would [blank]
  • The "would" at the beginning applies to both verbs.
• When two verbs share a helping word like "would" and are connected by "and," they need to be in the same form:
  • 'would increase' uses the base form "increase"
  • So we need the base form after "and" too: "create"

The correct answer is B. create

The sentence is saying: The lock would increase the salinity AND would create a barrier (the "would" applies to both actions).

GRAMMAR CONCEPT APPLIED

Parallel Structure with Shared Helping Words

When you connect two verbs with "and" and they share the same helping word (called a modal auxiliary in grammar terms) like "would," "could," "should," or "will," both verbs must be in the same form – specifically, the base form:

Pattern: [Subject] + [helping word] + [base verb 1] + and + [base verb 2]

Example 1:

• ✓ Correct: The new policy would reduce costs and improve efficiency.
  • Both "reduce" and "improve" are base forms sharing "would"
• ✗ Incorrect: The new policy would reduce costs and improves efficiency.
  • "Improves" doesn't match the base form pattern

Example 2:

• ✓ Correct: The students could complete the assignment and submit it online.
  • Both "complete" and "submit" are base forms sharing "could"
• ✗ Incorrect: The students could complete the assignment and submitting it online.
  • "Submitting" breaks the parallel structure

In this question:

• The lock would increase the salinity and create a barrier.
  • Both "increase" and "create" are base forms sharing "would"
• The helping word "would" applies to both actions, so both verbs must be in base form to maintain parallel structure.