Select the most appropriate option that can substitute the highlighted segment in the following sentence. If there is no need to substitute it, select ‘No substitution required’.
I enjoy learn languages because I like them.

Correct option is C

The verb "enjoy" is always followed by a gerund (verb + ing), not the base form or infinitive.
Correct Usage: I enjoy learning languages.
Incorrect: I enjoy learn languages.
(Here, "learn" is in base form, which is grammatically incorrect after "enjoy")

Certain verbs are always followed by a gerund (verb + ing):
Examples: enjoy, avoid, consider, suggest, deny, finish, etc.