I was going to mention the very same thing: Questions 14, 17 and 19. There may be more, but those are the ones I encountered. I see that there ARE some questions where Other is a choice with the text box included for an explanation. Not so for 14, 17 and 19.
Looks like no one bothered to test the survey before e-mailing it to developers. Some questions have a text box for "other" where pre-selected answers are inappropriate. However, using the "other" responses prevents the form from being submitted.
We are fixing it right now. Stay tuned! Sorry for the inconvenience.