in the single choice type question, if the answer has picture, when the participant scroll down to see the picture, they always forgot the question. then again scroll up to see the question ,they scroll down to the answer....
they give me this feedback, i understand that's real a problem,but i have no idea to solve this problem.
any suggestion or solution?

You can try with some column display.

column is ok for the text answer. but for the wide picture, it's not the best solution.especially for the mobile user.

Try position="fixed" for the question text element:

www.w3schools.com/css/css_positioning.asp
www.w3schools.com/css/tryit.asp?filename=trycss_position_fixed



.

tried, but actually when you scroll down, the answer picture will cover the question picture.it seemed the answer Z index is higher than question.