Research Experience for Undegraduates

This might be a pretty simple question, but I’m hoping there’s someone out there that knows the answer.

I’m applying to a lot of REU’s and I know they’re highly competitive. The thing is, I noticed that when they ask for a major GPA, they only list one option. Since I’m double majoring in Biology and Psychology, what am I supposed to do? One is obviously higher than the other, (3.6 vs. 4.0), but I’m thinking of choosing whichever major is more related to the REU, even if it’ll hurt my chances. What do y’all think?