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: Pediatrics
In an Autosomal Recessive (AR) disorder, one parent is normal and the other is carrier and the child is also affected. What is the reason - 
Select and explain. 
A. Germ line mosaicism, B. Genomic imprinting, C. Genomic imprinting, D. Uniparental disomy
D: Uniparental disomy
Answer: D: Uniparental disomy 
Explanation: Ans. is 'd' i.e., Uniparental disomy