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
If a drug is active against the pre-erythrocytic stage of the malarial parasite, it will be useful as: 
Select and explain. 
A. Suppressive prophylactic, B. Causal prophylactic, C. Clinical curative, D. Radical curative
B: Causal prophylactic
Answer: B: Causal prophylactic 
Explanation: None