Which is a fused sentence?
a. felicia likes to watch old movies and listen to old rock music.
b. juanito likes to play drums that he makes out of old cans.
c. my dad doesn’t have a hobby he is too busy working.
d. i enjoy playing video games because they are so exciting.

The correct answer is C. My dad doesn’t have a hobby he is too busy working.

Explanation:

A sentence is considered as fused if the sentence contains two independent clauses together without proper punctuation such as a semicolon or a transition. This type of grammar error can be seen in "My dad doesn’t have a hobby he is too busy working" because in this sentence there are two independent sentences each with a subject, verb and even object/complement "My dad doesn’t have a hobby", and " he is too busy working" but there is no punctuation or transition between them.

is that the whole question?

the correct answer would be d.