Answer: If I received this question, the only viable option in my opinion is answer choice C.
Explanation: I believe that it cannot be A due to the fact that amendments have passed and effected things other than voting rights and taxes (3rd amendment, gun rights). I believe that is cannot be B because amendments affect people under 18 (Tinker vs Des Moines). I also believe that it cannot be D due to the fact that as long as 2/3 of the Senate and House approve it and 3/4 of the states ratify it, amendments are still allowed. You could argue for the answer C since it might not pass because most proposed amendments do not pass. 27 amendments have been approved while 6 have been denied. A lot more have been discussed but ultimately not submitted to the States.