The correct answer is C) Aspirational group
Explanation:
An aspirational group refers to a group an individual wants to join. This is usually because the individual considers the values, ideas, practices, and behavior of the group are positive or fit his/her ideas and values. Additionally, aspirational groups are part of reference groups (groups that individuals use as standards) and include groups in which there are interaction and sense of identity or groups that include people with common features but not interaction.
In the case presented, the environmental activists are an aspirational group because Tim wants to join this group and considers the values, ideas, etc. of this group are ideal, this explains why Tim admires the actions of this group. Moreover, this group holds similar values, beliefs, etc. to those of the high-school student.