Single space, double space, or half space?

for college admission and scholarship essays should you:

a) single space
b) double space
c) half space
Update: right now my essay is single spaced, with a space between each indented paragraph...like this:

oiuwoeiuoiutouweiurwoeutoweiutwoiutoweut...

uhgjskghldjgsdkljlsdkjglksdjfksldniosd...
Update 2: it didnt come out the way i typed it
3 answers 3