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
Which of the following is seen in Angelman Syndrome 
Select and explain. 
A. Uniparental disomy of maternal Chromosome, B. Obesity, C. Defective genomic imprinting of maternal chromosome, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Angelman Syndrome

Uniparental disomy of Paternal Chromosome
Defective imprinting of maternal Chromosome

Clinical features
Mental retardation
Happy puppets.