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: Pathology
The Triat in which the parents are clinically normal and only siblings are affected but males and females are affected in equal propoions is: 
Select and explain. 
A. AD, B. AR, C. XLD, D. XLR
B: AR
Answer: B: AR 
Explanation: AR