One More SAT II--Suggestions?

<p>I am currently a high school junior. I am in AP Chemistry and AP Calc (as my science and math classes) and I took Precalculus Honors last year. I am planning to take the Math II Subject test and the Chemistry Subject test in June. I know that 2 SAT Subject tests are required for many good colleges, but some (Harvard) require 3. I just want to be on the safe side and take one more. Any suggestions for an easy SAT Subject Test to self-study for? I took Biology Honors in 9th grade, and I can probably study up on that. I'm also in physics (not AP) this year. Which is easier to self-study? I am also in AP World History, but history multiple choice is not my strong point. I need as high a score as I can get. I know I have a chance of getting VERY high scores on the Math II and Chemistry Subject Tests, but which other one should I take (and possibly self-study for)?</p>