What Do People Following the Norm of Reciprocity Do When

What do people following the norm of reciprocity do when communicating during the early stages of relationship development?

A) They encourage the other person to open-up by not saying anything themselves.
B) They avoid topics already mentioned by their relationship partner.
C) They try to match the qualities of the partner's communication, in terms of explicitness, humor, or politeness.
D) They try to make the person feel comfortable by sharing something private about themselves.