You are not the exception
Hacer una voltereta thats how you say it in spainsh hope it helps
The answer is A. Tú tocas el piano. Because Tu tocas is the only correct way of saying you are playing the piano in this instance. C is saying "tocan" which is wrong because it's saying you but then using a the group form of playing. The same thing with B, it's also using the group form of playing and it's past tense. And D is using the I form of playing not the you form.
Answer:
cuando quieres que sea la fiesta