Brainzilla IQzilla 2 test question - coloured squares in a 3x3 grid

I need your help solving this question

I’ve been trying to solve this question for half an hour, but I can’t find a pattern. Can someone please help me? I’m very curious about the solution.

We have to figure out which square(A, B, C, D,…, H) we have to put in the lower right corner of the image on the left based on some logic.

Source: Brainzilla