Answer:
3 and 4
Step-by-step explanation:
These two choices seem to be the most likely as they make the most sense. Think about it. Customs and social norms are not required by law. Members of a cultural group tend to know their customs. They usually learn by a very young age, do's and don'ts that will last them a lifetime. Customs do tend to be enforced by social pressure. How many times have you accidentally broken a social norm and you've gotten stares and glares of people who would never do that. And yes, customs are shared by members of a group and they do help a person to 'fit in'. These kinds of questions, try to answer them based off your experiences and observations. That helps because then you have application to the real world.
Hope that helps.