Research on teen smoking and other deviant behaviors has found that the most important factor in statistically predicting if a teen will take up a particular deviant behavior is the presence or absence of peers who also engage in that behavior. This is probably because the other teens are acting:

in ways that are closely related to family, in cooperation with schools and the media, as the most powerful long-term force in the lives of their friends.

Explanation:

It is proven that adolescents, faced with their development and lack of maturity of cognitive development and their social values, acquire, test and analyze certain addictions such as smoking, not only as a method of rebellion but also as knowledge of the space of the unknown.

answer; eliminate parking problems in cities, because a car took up only half as much space as a horse and buggy;

i have to go with a for this one