Choose the sentence that correctly uses the expression a far cry from to compare city life and rural life.

Introduction / Context:
This improvement question checks your control of the idiom a far cry from, which is used to say that one situation is very different from another. The sentence compares life in the centre of a huge city with life in the countryside, so the idiom is very appropriate if used correctly.

Given Data / Assumptions:
The key structure should be is a far cry from, followed by a noun or gerund phrase that describes the contrasting situation. Any replacement that changes from to than or that alters far cry into something else will likely be incorrect. The rest of the sentence, living in the rural countryside, is sound and does not need major alteration.

Concept / Approach:
In standard English we say something is a far cry from something else, not a far cry than or far cry than. The preposition from is essential in this idiom. We also avoid adding unnecessary verbs like ruing, which means regretting, because they change the meaning entirely. Therefore, we focus on the option that keeps is a far cry from as a fixed chunk and preserves the intended comparison.

Step-by-Step Solution:
First, look at option A: Living in the heart of New York city is certainly a far cry from living in the rural countryside. This uses the idiom exactly as it should be used.Second, examine option B: is a far cry than. This replaces from with than, which is wrong in this idiom.Third, examine option C: is certainly ruing living in the rural countryside. This introduces the verb ruing, which changes the meaning to regretting rather than comparing.Fourth, examine option D: is certainly far cry than. This removes the article a and again uses than instead of from, creating two separate grammar problems.Finally, confirm that only option A captures the correct idiom and keeps the sense of a strong contrast between city and rural life.

Verification / Alternative check:
You can verify the idiom by recalling similar sentences: This small town is a far cry from the busy capital or His new job is a far cry from his old routine. In all such examples, the structure a far cry from remains fixed. If you substitute than, the sentences immediately sound wrong. This confirms that option A follows the established pattern.

Why Other Options Are Wrong:
Option B misuses the preposition than, which normally follows adjectives like greater or different, not the idiom a far cry. Option C introduces a new verb ruing, which both changes the intended meaning and breaks the comparison structure. Option D removes the article and still uses than, leaving far cry than as an incorrect fragment. These deviations from standard idiomatic English make the options unsuitable.

Common Pitfalls:
A frequent mistake in idiom questions is to mix patterns. Students remember that than often follows comparative expressions and incorrectly attach it to idioms that actually require from. Another pitfall is to think that replacing words with rarer vocabulary such as ruing automatically improves a sentence. In reality, clarity and correctness matter more than unusual word choice. Always recall the full idiom as you have seen it in real reading.

Final Answer:
The correct sentence is Living in the heart of New York city is certainly a far cry from living in the rural countryside.