What should I do this summer?

What should I do this summer?

I’m a rising junior, I’m going to be a math major, and for the past two summers I’ve done number theory classes on AoPS.

These are my plans for the summer so far:

1. Study for the ACT

2. Study for the AMC 12 so I can qualify for AIME

3. Do AoPS CrowdMath, which is a mass math research project that may or may not get published. It’s the only high school-friendly math research I’ve found.

Other than that, I’m thinking of volunteering at my local art museum because I’m interested in the fine arts and volunteering, OR taking an online math class affiliated with a well known uni in something not usually covered in HS curriculum. Btw I was rejected from SUMaC and PROMYS earlier this year which were my original ideas for the summer.

The third option is for me to take an intro to comp sci booster over the summer, which I was originally going to take next summer, as prep to take AP Comp Sci A my senior year. If I took the booster class this summer then I could switch my schedule around and take AP CS my junior year and AP Stat my senior year, instead of the other way around. The benefit of this plan is I don’t have to worry about making time to take this booster class next summer.

I know people will say “do what you love, don’t do it for college,” but all three of these ideas get me equally excited so that is really not an issue. I would just like input on which ec will further my application the most :)

Thank you in advance!