Which is the best example of positive peer pressure?

Which is the best example of positive peer pressure?
Select one of the options below as your answer:

A. Jessica dresses in nice designer clothes every day at school. Everyone else at the school wants to be like her.
B. Javier invites his fellow seniors to his house after the prom. He is not serving alcohol, and his parents will be there.
C. Lindsay starts a yoga group with several friends from school. More and more students join the group each week.