Correct sentences:
a. April loved hiking; she also excelled at gymnastics.
c. Felicia loved the animation style known as anime; she grew up watching animated series from all over the world.
These sentences are correct because the semicolon carries out its function here: to join two independent clauses that are closely related to each other.
b. is incorrect because when listing things in a sentence, a comma is more suitable.
d. is incorrect because the semicolon here abruptly interrupts the idea of the sentence. A comma would not be possible here either.
