Healthy People Tend to Be Happier Than Unhealthy People

Healthy people tend to be happier than unhealthy people.From this kind of information,which of the following (if any) can we conclude?​

A) Good health increases people's happiness.
B) ​Happiness increases people's efforts to maintain their health.
C) ​Certain genes that tend to increase happiness also tend to improve health.
D) ​We can draw none of these conclusions.