Which do you think makes people more likely to follow the norms of society; rewards or punishments? Why?

Depends on what you think ...

if you think rewards make people more likely to follow the norms of society then it could be because they get something out of it and it is some sort of bribery or motivation,

if you think punishments make people more likely to follow the norms of society, it could be because they don't want the punishment and it is threatening.