Correct answer = C. Ticagrelor.
Of the four P2Y12 ADP receptor antagonists, ticagrelor is the only one that reversibly binds the receptor. This is important when it comes to compliance. If a patient is not compliant, then the antiplatelet activity of ticagrelor stops when the drug is missed (since the platelets inhibited are not irreversibly inhibited as they would be with aspirin, clopidogrel, or prasugrel). On the other hand, the waiting period prior to surgery may be shorter in patients taking ticagrelor since it takes less time for the antiplatelet effect to wear off.