In an English sentence improvement and relative clause question, choose the best alternative to correct the sentence: "He is one of those who likes to help others."

Introduction / Context:
This sentence improvement question tests your understanding of subject verb agreement in complex noun phrases with "one of those who". The original sentence "He is one of those who likes to help others" appears almost correct, but there is a subtle error in verb agreement inside the relative clause. Such questions are common in competitive exams that focus on advanced grammar and usage.

Given Data / Assumptions:

• Original sentence: "He is one of those who likes to help others."
• Key structure: "one of those who ..."
• Options adjust the relative clause part in different ways.
• The idea is that he belongs to a group of people who like to help others.

Concept / Approach:
In the structure "one of those who", the relative pronoun "who" usually refers to "those", which is plural. Therefore, the verb in the relative clause must be plural ("like"), not singular ("likes"). The sentence describes a whole class of people who like to help others, and he is one member of that class. The correct alternative must preserve this plural agreement and natural wording.

Step-by-Step Solution:
Step 1: Identify the key phrase: "one of those who". The noun "those" is plural. Step 2: Note that the verb after "who" should agree with "those" and therefore be plural. Step 3: The correct form should be "those who like to help others", not "likes". Step 4: Examine option "those persons who like to help others": this is grammatically correct, but the word "persons" is unnecessary and makes the phrase less natural. Step 5: Examine "those who like to help the other": the phrase "the other" is incorrect here; we help "others" in general, not one specific other. Step 6: Examine "those who like to help others": this version is concise, grammatically correct, and idiomatic. Step 7: "No improvement" would keep the singular verb "likes", which conflicts with the plural antecedent "those".

Verification / Alternative check:
Compare similar examples: "She is one of the students who study hard" (not "studies hard"). Here, "who" refers to "students" (plural), so the verb is "study". Similarly, "He is one of those people who speak the truth" (not "speaks the truth"). Grammar references confirm that when "one of those" is followed by a relative clause, the verb in the clause agrees with the plural noun, not with "one". This supports using "like" rather than "likes".

Why Other Options Are Wrong:

• those persons who like to help others: Grammatically acceptable but stylistically heavy; the word "persons" is not required and the exam usually prefers a more natural expression.
• those who like to help the other: The phrase "the other" is incorrect here because it refers to a specific single person, whereas the sentence means helping people in general.
• No improvement: Keeping "likes" would make the verb agree with "one" instead of "those", which is considered incorrect in standard exam grammar for this structure.

Common Pitfalls:
A frequent error is to make the verb agree with "one" instead of "those", writing "one of those who likes" instead of "one of those who like". This happens because the noun "one" is closer to the verb. To avoid this mistake, always identify the true antecedent of the relative pronoun "who". In such structures, think: "those (who like to help others)" and then add "He is one of". This mindset automatically leads you to use a plural verb in the relative clause.

Final Answer:
The sentence should be improved to: "He is one of those who like to help others."