That's not what the question asks. It asks "do you identify as part of an under-represented group" with an option for "I identify as a woman". That's not the s

That's not what the question asks. It asks "do you identify as part of an under-represented group" with an option for "I identify as a woman". That's not the same as a straight gender m/f question. I can imagine that some women felt they weren't under-represented and didn't primarily "identify as a woman" even if they were one. Consider the reverse question with s/woman/man/ - how many men would pick "I identify as a man" vs "I do not identify as part of an underrepresented group". It's a leading question. Bear in mind on that question the vast majority of respondents were just a shrug: either no response, explicitly saying they didn't want to answer, or not identifying as part of such a group.