In the following sentence improvement question, the underlined part is within a stone's throw: My office is within a stone's throw from the university. Choose the best replacement, or select No improvement if the phrase is already correct.

Introduction / Context:
This question focuses on the correct use of a common distance-related idiom: at a stone's throw. The sentence is My office is within a stone's throw from the university, and within a stone's throw is underlined. The intended meaning is that the office is very close to the university. While the phrase within a stone's throw is sometimes heard, the more standard and widely accepted form in exam English is at a stone's throw from a place.

Given Data / Assumptions:

• Sentence: My office is within a stone's throw from the university.
• Underlined phrase: within a stone's throw.
• Options: in a stone's throw, within a stone throw, at a stone's throw, No improvement, beyond a stone's throw.
• Meaning: The office is very near the university.

Concept / Approach:
The idiomatic expression usually taught and tested is at a stone's throw from, meaning at a very short distance from. The preposition at works with stone's throw to form a set phrase, and from introduces the reference location. Within a stone's throw is less common and, combined with from, sounds slightly awkward in formal writing. Also, a stone throw (without the possessive apostrophe s) in option B is incorrect. Therefore, at a stone's throw fits the standard pattern best.

Step-by-Step Solution:

Verification / Alternative check:
Read the improved version aloud: My office is at a stone's throw from the university clearly communicates that the office is very close to the university. The phrase at a stone's throw from is the one you will frequently find in example sentences and language guides. In contrast, My office is within a stone's throw from the university is understandable but sounds slightly off to trained ears, as within is more often paired with of in such expressions (within a stone's throw of), which is not one of the options.

Why Other Options Are Wrong:
Option A (in a stone's throw) is unidiomatic; we do not normally say in a stone's throw to describe distance. Option B (within a stone throw) drops the necessary possessive s and therefore breaks the noun phrase; it should be stone's throw, not stone throw. Option D (No improvement) is not ideal because the given combination within ... from is less standard than at ... from in exam contexts. Option E (beyond a stone's throw) reverses the meaning, suggesting that the office is not very close, which does not match the likely intention of the sentence.

Common Pitfalls:
Students sometimes pay attention only to vocabulary and not to the specific prepositions that complete an idiom. However, prepositions are crucial in fixed phrases like at a distance, in the vicinity, and at a stone's throw from. Another pitfall is to assume that if a phrase is understandable, it must be the best choice. In competitive exams, the standard, textbook version of an idiom is preferred even if slight variations are used informally in speech.

Final Answer:
The best improvement is at a stone's throw, giving: My office is at a stone's throw from the university.