How to randomly present pictures in only one of my four groups

Hi everyone, I have a question about how the loop setting. I have four groups of pictures, and there are five pictures in each group. I want my participants to only see randomly one of the four groups’ pictures. But if I use the loop and block function, it seems like all of the four groups will be presented with a random sequence. Is there any way to randomly present only one of the four groups’ pictures? Thank you so much if you have any advice!!!

Hopefully this thread now answers this question How to create between subjects online experiment - #2 by Becca