In what way do people discriminate against teenagers?

Discrimination against children and youth is caused by the bias adults have for other adults that causes them to discriminate against young people.

Well not having the multiple choice I can only guess, but here are a few.

1 - Thinking teens are not old enough to be considered smart, wise, or responsible

2 - People don't think teens have the right to voice their opinion, because how young they are.

3 - people think all teenagers are the same because of the stereotypes that are in place for teenagers such as laziness, irresponsibility, and rebelliousness.