Karan will arrive in . . . . . . . . hour. A. a B. an C. the D. none of these

The correct answer is: A. a

The word “hour” is a countable noun, so it takes an indefinite article “a” or “an”.

• “A” is used before singular nouns that start with a consonant sound.
• “An” is used before singular nouns that start with a vowel sound.

In this case, the word “hour” starts with a consonant sound, so we use the indefinite article “a”.

The other options are incorrect because they are definite articles. A definite article is used to refer to a specific person, place, thing, or idea. In this case, we do not know when Karan will arrive, so we cannot use a definite article.