Alison's school classmates make a point of ignoring her and they purposely exclude her from participation in any of their after-school social events. their treatment of alison most clearly

Their treatment of Alison most clearly illustrates Ostracism.

Explanation:

Ostracism occurs when a social group intentionally excludes someone and does not accept them as member of the group.

This forms part of social rejection when one is not being welcomed within a group or by a certain individual if this continues for a long time an ostracized individual may start to feel lonely which may lead to depression or aggression.

Like Alison is being ignored and excluded from after school activities which may make her be a loner and start to feel unworthy or if may start to make her violent towards others as a defensive mechanism or a way of taking her emotions out.

Their treatment of Alison most clearly illustrates Ostracism.

Explanation:

your answer is "graduates" hope this