Explanation
Correct Answer: (b) an
Detailed Explanation
This question tests your knowledge of the rules governing indefinite articles (a versus an).
The fundamental rule for choosing between these two articles does not depend on how a word is spelled, but rather on its initial sound:
Rule 1: If a word begins with a consonant sound⟹Use the article "a"
Rule 2: If a word begins with a vowel sound⟹Use the article "an"
Let's look closely at the word "honest":
Spelling: It begins with the consonant letter 'h'.
Pronunciation: The letter 'h' is completely silent. The word is pronounced as "on-ist" (/ˈɒn.ɪst/), which starts with a distinct vowel sound (the short 'o' sound).
Because it produces an initial vowel sound, it strictly falls under Rule 2 and requires "an".
This perfectly matches the structure for option (b): "He is an honest man."