The most appropriate topic for a group of high school students would be how to resist peer pressure and avoid harmful drugs. Option A is correct.
Drug use in high school is very common due to the fact that adolescents start to discover new things that cause them new sensations and feel very atracted to them, such as alcohol and drugs, specially in order to fit in a group. The most common drug consumed by teens is marijuana.
Option B would be a topic for older people, option c for adullts or youth and the last one for children.