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: Dental
True about the statement is: When null hypothesis is rejected when it is true? 
Select and explain. 
A. Type I alpha error, B. Type II beta error, C. Gamma error, D. All of the above
A: Type I alpha error
Answer: A: Type I alpha error 
Explanation: None