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
In which of the following phases of clinical trials healthy normal human volunteers paicipate - 
Select and explain. 
A. Phase I, B. Phase II, C. Phase III, D. Phase IV
A: Phase I
Answer: A: Phase I 
Explanation: Ans. is 'a' i.e., Phase I o Phase I involves normal human volunteers.