Well, I consider forced-choice polls of that form a bit obnoxious, whether insulting or not, because I feel like I'm being tricked into saying something I don't believe. E.g., "My favorite pizza topping is: (a) pepperoni, (b) sausage, (c) mushroom" is an obnoxious poll, but is not insulting to anyone. That contributes somewhat. Had you added options that allowed for the possibility of your implicit assumptions being false (e.g., "none of the above", "I don't have a favorite pizza topping", etc.) that element would have been removed.