Final answer:
A 35-year-old man with schizophrenia treated with typical antipsychotics likely has Antipsychotic-induced parkinsonism, as his symptoms resemble Parkinson's disease due to the effect of the medications on dopaminergic neurons in the brain.
Step-by-step explanation:
The most likely diagnosis for a 35-year-old man with a history of schizophrenia taking typical antipsychotics for 6 months who presents with rigidity and tremors is B. Antipsychotic-induced parkinsonism. Typical antipsychotics can lead to side effects similar to the symptoms of Parkinson's disease due to their action on dopaminergic pathways in the brain. Signs and symptoms such as the characteristic pill-rolling tremors, muscle rigidity, and reduced mobility are indicative of the impact of these medications on the substantia nigra region of the brain where dopamine-producing neurons are primarily located. Antipsychotic-induced parkinsonism occurs because antipsychotic medications block dopamine receptors and decrease dopamine neurotransmission, leading to an imbalance that mimics Parkinson's disease.