The correct answer is D. no article.
The word “fiction” is an uncountable noun, which means it cannot be used with a definite or indefinite article. For example, you
would not say “I read a fiction novel” or “I read the fiction novel.” Instead, you would say “I read fiction novels” or “I read a lot of fiction.”In this case, the sentence is about Umesh’s general enjoyment of reading fiction novels. Therefore, we do not need to use an article.
If the sentence were about a specific fiction novel, then we would use an article. For example, we could say “Umesh enjoys reading the fiction novel ‘The Lord of the Rings.'”
I hope this explanation is helpful!