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: Pharmacology
Drug of choice for exo-erythrocystic stage of malaria is ? 
Select and explain. 
A. Chloroquine, B. Primaquine, C. Proguanil, D. Mefloquine
B: Primaquine
Answer: B: Primaquine 
Explanation: Ans. is 'b' i.e., Primaquine