In Their Studies,Clark and Mills Found That Tit-For-Tat Exchanges ___________

In their studies,Clark and Mills found that tit-for-tat exchanges ___________ people's liking for each other when _______________.

A) boosted; their relationship was relatively formal
B) diminished; they sought superficial friendship only
C) boosted; their relationship was very informal
D) diminished; their relationship was casual