Final answer:
Risperidone primarily blocks dopamine D2 receptors, helping to treat symptoms of disorders like schizophrenia by reducing overactive dopamine neurotransmission.
Step-by-step explanation:
The atypical antipsychotic risperidone primarily works by blocking a certain type of dopamine D2 receptor, which is A) Dopamine D2 from the options provided. Risperidone antagonizes D2 and serotonin type 2 receptors, among others, and is used to treat symptoms associated with overactive dopamine neurotransmission in disorders like schizophrenia.