According to research, one's level of happiness is related to all of the following except a. self-esteem b. optimism c. physical attractiveness d. close friendships

I would say that the best answer for this is option C. Based on the researches done, self-esteem, optimism, and close relationships are related to one's level of happiness and that would be except for physical attractiveness. Not everyone is physically attractive but because of self-esteem, this made them feel better about themselves. 

The rest don't make sense so i say the first one.