From the passage about nuclear security, choose the correct preposition to complete the blank in the sentence: "The main failings were of conception and a political willingness to settle _________ easy options."

Introduction / Context:
This question is based on a passage discussing nuclear security and political decision making. It focuses on the correct preposition that collocates with the phrasal verb "settle" when we mean accepting something less than ideal. Correct use of prepositions is crucial for accurate comprehension and written expression, especially in formal analytical writing.

Given Data / Assumptions:

• The sentence fragment is: "The main failings were of conception and a political willingness to settle _________ easy options."
• Options are: to, of, from, for, over.
• The context suggests that political leaders accepted options that were too easy rather than more demanding ones.
• We must choose the preposition that forms a standard idiom with "settle".

Concept / Approach:
The key idiom here is "to settle for something", which means to accept something that is less than what one really wants or that is second best. Many English phrasal verbs require specific prepositions. Choosing the wrong one changes or destroys the intended meaning. Therefore, we must recall which preposition appears with "settle" in this usage.

Step-by-Step Solution:
Step 1: Recall the common phrase "settle for less" or "settle for second best", which means to accept an inferior choice. Step 2: Understand that in the passage leaders are criticised for accepting "easy options" instead of stronger, more effective measures. Step 3: Match this idea with the pattern "settle for easy options", which fits both meaning and usage. Step 4: Test "settle to easy options". This sounds unnatural; "settle to" is not the standard idiom in this sense. Step 5: Test "settle of easy options". This is grammatically wrong and does not form any recognised collocation. Step 6: Test "settle from easy options". This also fails as there is no established phrase with "settle from" in this context. Step 7: Test "settle over easy options". "Settle over" might appear in disputes, but not in the sense of accepting lower quality alternatives. Step 8: Therefore, the only correct and idiomatic form is "settle for easy options".

Verification / Alternative check:
You can confirm by inserting the phrase into similar sentences: "Instead of working hard, they settled for easy solutions" clearly communicates that they accepted simpler but weaker choices. Replacing "for" with any other preposition makes the sentence awkward or incorrect. This supports the choice of "for" as the correct preposition.

Why Other Options Are Wrong:

• to: "Settle to" is not used in this sense and sounds ungrammatical here.
• of: "Settle of" has no meaning in standard English and breaks the idiom.
• from: "Settle from" does not form a recognised phrase with the intended meaning of acceptance.
• over: Used in contexts like "settle over a drink" or "settle over an issue", but not for accepting inferior options.

Common Pitfalls:
Learners sometimes treat prepositions as interchangeable or rely on direct translation from their first language. However, English phrasal verbs are often fixed expressions. A very common pitfall is to choose a preposition that "sounds" acceptable without recalling the idiom. To improve, make a list of common combinations such as "agree on", "decide on", "settle for", "argue over", and revise them regularly.

Final Answer:
The correct preposition is for, giving the phrase "settle for easy options".