In this English grammar improvement question, choose the alternative that best improves the bracketed part of the sentence: "Einstein was one (of the wisest men) that ever lived."

Introduction / Context:
This sentence improvement question checks your understanding of how to correctly use comparative and superlative structures such as "one of the wisest men". Competitive exams often test this pattern, because many learners get confused between singular and plural forms and between superlative structures like "the wisest man" and "one of the wisest men". The sentence talks about Albert Einstein and wants to say that he belonged to the group of the wisest men who have ever lived.

Given Data / Assumptions:

• The original sentence is: "Einstein was one (of the wisest men) that ever lived."
• The bracketed part is "of the wisest men".
• The options offer alternative phrases, including "of the wisest man", "wise man", "wisest man", and "no improvement", plus a distractor.
• The intended meaning is that Einstein was among the group of the wisest men in history, not the only one.

Concept / Approach:
The structure "one of the + superlative adjective + plural noun" is standard when we want to say that someone belongs to a group of people who are all at the top in some quality. For example, "one of the greatest scientists", "one of the most beautiful cities", or "one of the wisest men". Because "one of" clearly indicates a group, the noun that follows must be plural. Hence, "one of the wisest men" is correct, whereas "one of the wisest man" is grammatically wrong. The superlative "wisest" is also appropriate because we are comparing Einstein with all other men who have ever lived.

Step-by-Step Solution:
Step 1: Identify the pattern "one of the ..." and recall that it must be followed by a plural noun. Step 2: Look at the existing bracketed phrase "of the wisest men". It correctly uses the plural "men". Step 3: Check option A "of the wisest man". This uses a singular noun after "one of the", which is incorrect. Step 4: Check option B "wise man". This ignores the "one of the" structure and changes the meaning to "Einstein was one wise man", which is not the same. Step 5: Check option C "wisest man". This would give "Einstein was one wisest man", which is grammatically wrong. Step 6: Since the original bracketed phrase is already correct, "no improvement" must be selected.

Verification / Alternative check:
Compare with similar sentences: "She is one of the best players on the team", "This is one of the most interesting books I have read". In all these, the word after the superlative is plural. Likewise, "Einstein was one of the wisest men that ever lived" follows the same pattern, confirming that no change is needed. Any alternative that makes the noun singular breaks the standard grammar rule for this construction.

Why Other Options Are Wrong:
"Of the wisest man" is wrong because a singular noun cannot follow "one of the". "Wise man" removes the superlative and does not express the idea that Einstein belonged to the very top group. "Wisest man" without "of the" cannot fit smoothly into the original sentence in that exact position. The distractor "of all wise men" also changes the structure and meaning. Therefore, these are all inferior to the original phrase.

Common Pitfalls:
A frequent mistake is to focus only on the superlative adjective and forget the number of the noun. Candidates sometimes think "one of the wisest man" sounds more natural, but it is grammatically incorrect. Another pitfall is trying to change a correct phrase simply because an exam question asks for improvement. Always remember that in such questions "no improvement" is often the right answer when the original phrase is already correct standard English.

Final Answer:
The correct choice is no improvement, so the sentence should remain "Einstein was one of the wisest men that ever lived."