What is a way to maintain your social health?
a. be sure to get at least nine hours of sleep each night.
b. take vitamins every day.
c. be a loyal, truthful and dependable friend.
d. take part in regular physical activity.?

Hello there.

Question: What is a way to maintain your social health?  
a. be sure to get at least nine hours of sleep each night.  
b. take vitamins every day.  
c. be a loyal, truthful and dependable friend.  
d. take part in regular physical activity.

It would be C. be a loyal, truthful and dependable friend. All the other options are more related to physical health rather than social health. 
As C is the only option related to social health then i presume that would be the answer. 

In short, Your answer is C.

Hope This Helps You!
Good Luck Studying ^-^