Direction: Find out which part has an error and mark it as your answer. If…

Concept: 'Which' functions as a determiner or a selecting pronoun (as in 'which of the two candidates') only when the limiting phrase attaches directly to the interrogative word itself. 'Who' is always a pronoun, never a determiner, and is the standard interrogative for asking about a person's identity — including within a comparison — as long as the limiting phrase does not attach to 'who' directly.

Application: In 'Who is the better of the two candidates?', the phrase 'of the two candidates' modifies 'the better' (a comparative noun phrase functioning as the predicate — 'the better [one] of the two candidates'), not 'who'. Since the limiting phrase attaches to 'the better', not to the interrogative pronoun, this is not the 'which of X' selection pattern at all — it is structurally the same as 'Who is the tallest of the three brothers?', which is standard, unremarkable English. 'Who' is therefore correct in segment (A).

Cross-check: Testing each segment on its own confirms this:

• (A), 'Who is the,' — 'who' correctly asks about a person's identity; the limiting phrase attaches to 'the better', not to 'who' — standard usage.

• (B), 'better of,' — the comparative 'better' correctly pairs with 'of' (not 'than') when comparing exactly two items — standard usage.

• (C), 'the two candidates?,' — the definite article 'the' correctly marks the specific pair already referred to — standard usage.

Result: Every segment is grammatically sound, so the sentence 'Who is the better of the two candidates?' contains no error. The correct answer is 'No error'.

Additional Information

A common exam shortcut claims 'which' must replace 'who' whenever a choice is being made among a limited group of people (e.g., 'Which of the two brothers is taller?'). That pattern applies specifically when the limiting phrase ('of the two brothers') attaches directly to the interrogative word. It does not apply when 'who' is simply the subject of the sentence and the limiting phrase instead modifies a comparative/superlative noun phrase elsewhere in the sentence, as in 'Who is the better of the two candidates?' or 'Who is the tallest of the three brothers?' — both fully standard.