Milo Has Been Feeling Down for the Last Month or So

Milo has been feeling down for the last month or so. However, he cannot quite trace back to what may have caused this feeling to begin with. Aside from feeling sad, he cannot seem to eat or sleep as he normally does. He has never felt this way before and it is beginning to scare him because he is starting to feel as if there is nothing he can do to stop feeling this way. Which diagnosis currently seems to best fit Milo's symptoms?

A) bipolar disorder
B) generalized anxiety disorder
C) major depressive disorder
D) paranoid schizophrenia