Prevent images as answer choices from resizing in mobile version

Dear Qualtrics Community,
I am facing a problem related to the mobile version of my questionnaire.
I want to conduct a test where respondents have to choose the correct image out of 8 different choices. My questions are multiple choices questions with 8 choices in 4 columns and I also have an answer text which is "1.", "2." etc. and then for each of the eight choices I used the "insert graphic" option to upload the graphic part of the answer choices. Whereas the desktop version looks good, in the mobile version the graphic answer choices resize and become very small, whereas the numbers 1., 2., 3., follow the normal answer choice formatting set up. I also tried to eliminated the numbers in the answer choices, but it does not affect the resizing behavior. Do you have a code with which I could overwrite this? I am using the basic Desktop Theme.
Thanks a lot!