Which of the following drug  is associated with the lowest risk of causing extra pyramidal side effects?
In general all typical antipsychotics cause extra pyramidal side effects as they block dopaminergic activity and lead to unopposed increase in cholinergic activity. But Thioridazone possesses anticholinergic action and hence carries least risk of causing EPS. If the options included any atypical antipsychotic (Clozapine ,Olanzapine), then that would be the right answer as atypical antipsychotics has lower risk of causing EPS then all typical antipsychotics.
Chlorpromazine
Thioridazone
Haloperidol
Fluphenthixol