This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Psychiatry
Which of the following antipsychotic is a partial agonist at D2 receptors? 
Select and explain. 
A. Olanzapine, B. Ziprasidone, C. Aripiprazole, D. Quetiapine
C: Aripiprazole
Answer: C: Aripiprazole 
Explanation: All antipsychotics are antagonists at D2 receptors except Aripiprazole which is a partial agonist.