Among the alternatives, the only one that DOESN'T concern happiness is alternative C.
Happiness is not related to age at all. People can be happy at any age, or miserable at any age. Happiness is a state of mind that depends on people's expectations, goals, optimism, and other factors.
Happiness can be found when one is satisfied with as many aspects of life as they can possibly be, for example: if one is satisfied with the job, love life, hobbies, education, etc, this individual is most likely to be completely happy, regardless of the age. On the other hand, having less things in life which you're satisfied with, will affect directly your level of happiness.
