This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Biostatistics, Subject name: Social & Preventive Medicine
Rejecting a null hypothesis when it is true is called as? 
Select and explain. 
A. Type 1 error, B. Type 2 error, C. Type 3 error, D. Type 4 error
A: Type 1 error
Answer: A: Type 1 error 
Explanation: .