the third one, if you add the comma without the when then you would have a comma splice (when you put a comma between 2 independent clauses without a conjunction) adding the when before Cynthia makes the first part a dependent variable and makes it okay to add the comma!
Hope this helps! :)
The answer is A, uneven parallelism, because of "with" and "who".
A cell phone addiction is more likely to be prominent with women, women tend to use social media more.
