My answer, #2 below, is written "qu'il est". An apostrophe should separate these two adjacent vowels.
The so-called "right" answer, #1 below, is written "qui est" with no apostrophe between qui and est. My answer, #2, correctly has the apostrophe. Answer #1 is wrong; if not, please explain why not.
#1 La femme avec qui il est marié est très belle. Yours, marked as correct.
#2 La femme avec qu'il est marié est très belle. My answer, marked as wrong.