Homeostasis refers to
a.
the tendency of a cell to maintain a stable internal environment.
b.
the effect of natural selection on human evolution.
c.
the similarity of genetic traits to one another.
d.
a mixture or solution that is the same throughout.

A.

the tendency of a cell to maintain a stable internal environment.

Explanation:

depression is an ongoing sadness\lack of motivation. you feel and feel like its never going to get better. you're so sad to the point you think of death.

anxiety is an ongoing feeling of paranoia\ feeling like everyone is watching you and making fun of you. you get nervous easily and feel like the room is spinning.  

yes, they cause death every year. its a long, exhausting battle. only few make it through as sad as it sounds.

explanation:

one day because their over eating or whenever it kicks in their body