I will give a chocolate to friend of mine.

A. each
B. every
C. all

B. Each

Explanation:

I will give a chocolate to each friend of mine.

Explanation:

"chocolate" is singular indicating that it is "per" person.

option c which is all would not work as the grammar is incorrect as "friend" is also singular indicating once again one per person. So eliminate C.

option b would also not work as the beginning part of the clause is not functioning to where it would sound gramatically correct as the subject pronoun in the sentence is giving a chocolate to each friend (one per person). So this leaves one answer available, option A, each.