Andrea asks her friends to spread a nasty rumor about her opponent for the office of class president to attempt to damage his reputation in the days before the election. this is an example of

The answer is Instrumental Aggression.

Instrumental Aggression is aggression as a means to some goal other than causing pain. It is an intentional use of dangerous or harmful behavior to achieve some unimaginative goal. It can also be carried out to avoid punishments. In here, the main goal may be to confiscate the enemy's land or defend one's territory.