I believe the correct answer here is B. me; object of a preposition. We can see that between is a preposition, so everything after it becomes a prepositional phrase.
Answer:
B. Free association
Explanation:
Freud sat his patients down a lot and let them vent. He'd then make assumptions based on the person from this venting, or "free association."
It's not C. There should be a comma where the semi colon is