Question

Nestor belongs to the cross-country ski club at his college, but he is not a member of the downhill ski club. in terms of basic social categories, nestor's cross-country fellow club members are the _____ and the members of the downhill ski club are the _____."

Answer 1

The answer is in-group; out-group
In sociology term, in-group refers to the group of people that we identify as being a part of based on certain similarities.
The out-group on the other hand, refers to the group of people outside the in-group, usually because they possess certain differences in traits or perception.