Treatment of an illness can include:
a. staying home
b. getting lots of rest
c. drinking plenty of fluids
d. all of these

Treatment of an illness can include all of these.

Staying at home is optional, and probably the best option so that you won't get anybody else sick and spread the germs.

Getting lots of rest is significant if you are sick, but not too much rest because your body does need to keep up that energy and you do need to move. Believe it or not, it might make you feel better if you got rest or even did your daily workout. Depends on the person you are.

Drinking plenty of fluids is so significant for when you are sick and the quickest way to make sure you won't get sicker or unhealthy. Our body is made up of water, so we need all the water we can get. Remember, it's reckoned to drink up to eight glasses of water each day. If you are sick, I would bump that up unless you are feeling sick to your stomach.