QUESTION 8 There is a "push_back()" function for vectors, but no "push_front()" function. Why do you think that is? a. It is not an efficient operation for vectors and with push_back(), there is no need for a push_fronto) b. Because of push back(), there is no need for push_fronto) c. It is not an efficient operation for vectors d. It was not put in the original version of the API. Adding it in now would break existing code. QUESTION 9 If the following expressions were both legal, which other expressions should be legal? stack names; auto iter = names.begin(); a. iter, names.end() b.iter.begin(), names.end() C. ++iter, names d. iter, names++