COS H4 to F1 denied, one semester left undergraduate, wanted to stamp F1 by travel

[ajakk]

I currently hold an H4 visa, but I wanted to get an F1 because I am aging out in May and this might interfere with my undergraduate studies. I also wanted to pursue further studies (graduate program). What is a good way to phrase this if the officer asks why I want to switch to F1 if I have an H4? Thanks