This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti-Malaria Drugs, Subject name: Pharmacology
If a drug is active against the pre-erythrocytic stage of the malarial parasite it will be useful as a: 
Select and explain. 
A. Suppressive prophylactic, B. Causal prophylactic, C. Clinical curative, D. Radical curative
B: Causal prophylactic
Answer: B: Causal prophylactic 
Explanation: If a drug is active against the pre-erythrocytic stage of the malarial parasite it will be useful as a Causal prophylactic. Stage killed Clinical Use Pre-erythrocytic Causal Prophylaxis Erythrocytic Clinical cure Suppressive Prophylaxis Exo-erythrocytic Radical cure Gametocytic Prevention of transmission