Select the most appropriate option to fill in the blank.
Reading ___ good book can be a relaxing way to spend an afternoon.

Correct option is C

The correct option to fill in the blank is (c) a.
Explanation:
The noun book is a singular countable noun, and it is mentioned for the first time in a general sense. Therefore, the indefinite article a is required before good book.
The sentence becomes:
Reading a good book can be a relaxing way to spend an afternoon.
Example:
· I bought a new dictionary.
· She wants to become a doctor.
Why other options are incorrect:
· (a) the: Used for a specific or previously mentioned book.
· (b) No article required: Incorrect because singular countable nouns require an article.
· (d) an: Incorrect because good begins with the consonant sound /g/.
Information Booster:
Use a before words beginning with a consonant sound:
· a university
· a European country
· a good book
Use an before words beginning with a vowel sound:
· an apple
· an hour
· an honest man