The correct option is C curator
Option D: A curator is a keeper or custodian of a museum. Hence the word can substitute for the given sentence and option D is correct.
Option A: A caretaker is a person who is employed to look after a building. It also refers to a person who looks after people or animals. It does not refer to a person who takes charge of a museum.
Option B: A warden is a person entrusted with the responsibility of an institution like a college, a church, etc.
Option C: A supervisor is a person who supervises or governs an activity.
These words do not mean exactly the same as the given sentence. Hence options A, B and C are incorrect.