Answer:
The correct answer is Who.
Step-by-step explanation:
Relatives clauses make references to the noun that precedes them. There are different types of relatives clauses. The words given in this exercise are both relatives clauses. However, the relative pronoun "which" is used for things or animals and the relative pronoun "who" is specially used for people. So, in this exercise, the most correct relative pronoun to use is "Who"