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
Which of the following is false about clinical trials of phases of drugs: 
Select and explain. 
A. Healthy volunteers are taken in Phase 1, B. Efficiency can be calculated in Phase 2, C. Maximum drug failure occurs in Phase 3, D. Post marketing surveillance is done in Phase 4
C: Maximum drug failure occurs in Phase 3
Answer: C: Maximum drug failure occurs in Phase 3 
Explanation: Maximum drug failure occurs in Phase 2.