What is depression ?
what is sadness ?​

Depression is a mood disorder that involves a persistent feeling of sadness and loss of interest. It is different from the mood fluctuations that people regularly experience as a part of life. Major life events, such as bereavement or the loss of a job, can lead to depression.

Sadness is a human emotion that all people feel at certain times during their lives. Feeling sad is a natural reaction to situations that cause emotional upset or pain. There are varying degrees of sadness. But like other emotions, sadness is temporary and fades with time. In this way, sadness differs from depression.

Hope it help

Ithink the answer is maybe a

The answer is constant.