What courses are the most important/difficult?

In your opinion, if you had to choose 3 courses, what do you think are the most important of the following five:

Microbiology, Organic Chemistry, Biochemistry, Anatomy, Physiology?

I plan on devoting some time studying for 3 of these courses to get a head start on pre-med and med school.

thanks.

<p>If you wanted to focus on three areas that are similar so that they will be easier to study, I'd choose microbio/orgo/biochem. If not, I'd choose microbio/biochem/phys just because they're the first, third, and fifth ones listed :P.</p>