The main clause is "Chris's chief interest was tennis".
The subordinate clause is "Which he was just learning to play" and it is an adjective clause because it describes what the "tennis" was like. Tennis is an object and this subordinate clause further describes that it is the tennis that he was trying to learn.
Hmmm... well you could say why you would like to go to college and what you want to accomplish from it for your thesis
It's setting. because it's where it happens
The answer would be B.
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