This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
The genotype of blood group A would be 
Select and explain. 
A. AB, B. AO, C. OO, D. BO
B: AO
Answer: B: AO 
Explanation: The genotype for a blood group can be AA OR AO blood groups are three genes Ia,Ib,Io Ref:Guyton and Hall textbook of medical physiology 12th edition,page number:155,156,157