challenge: What is unique about Aripiprazole's mechanism of action compared to other FDA-approved atypical antipsychotics?
  
  A. It has no effect on serotonin receptors
  B. It is an antagonist at 5-HT2A receptors only
  C. It is a full agonist at dopamine D2 receptors
  D. It is a partial agonist at dopamine D2 receptors and 5-HT1A receptors
  Answer: 