This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Physiology
A woman with infeility receives an ovary transplant from her sister who is an identical twin. What type of graft is it? 
Select and explain. 
A. Allograft, B. Autograft, C. Xenograft, D. Isograft
D: Isograft
Answer: D: Isograft 
Explanation: .