Sentence Correction

@vikram4689: Query - There is NO "if-then" statement how to identify if we require conditional

Hi Vikram,

Conditional "would" is used in the "then" clause of the "if..., then..." construction when the "if" clause is written in the past tense and the "then" clause shows uncertainty.

In the OG question, the "if..., then..." construction is apparent.

Conditional "would" is also used in a sentence that demonstrates any of the three following situations:

1. Expectation about future: The teacher expected that Ria would score the highest in the class.

2. Hypothetical situation: In order to learn boxing, Joe would need to take out some time from his evening job.

3. Assumption: Napoleon's army assumed that the supplies they were carrying during Russian invasion would last for over a month.

Notice that all these situations involve "uncertainty" in the outcome of the action in the future.

Affording strategic proximity to the Strait of Gibraltar, Morocco was also of interest to the French throughout the first half of the twentieth century because they assumed that if they did not hold it, their grip on Algeria was always insecure.

Notice the presence of the word "assumed" in the non-underlined portion of the sentence. This word prompts us to use conditional "would" because the following part of the sentence is talking about an assumption that involves uncertainty. The French assumed that if they did not capture Morocco, it would be difficult for them to hold on to Algeria.
This is an assumption that the French made. There was not any certainty that to would become true. Hence the correct answer choice (which you already know) uses conditional "would", even if there is no "if..., then..." construction there.

e-gmat customers can review this concept in details in the concept titled Verb Conditional in Level 2 Concepts.

Hope this helps.
Shraddha