1.)B. Invisibility
2.) D. Party
3.)B. Watch your neighbor's potion carefully
4.)A. Invent a new one
5.) B. Work out your escape
6.) A. Try to charm the professor into moving the test to another day
7.) C. Being able to take on anything
8.) A Release the Bludgers, causing confusion and giving you time to find your stick.
9.) C. Ignore the Head and sprint for the Great Hall to check it out
10.) C. Turn them into a toad
11.) C. Transfiguration