This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
A woman with infertility receives an ovary transplant from her sister who is an identical twin. What type of graft it is? 
Select and explain. 
A. Xenograf, B. Autograft, C. Allograft, D. Isograft
D: Isograft
Answer: D: Isograft 
Explanation: Ans. is 'd' i.e., Isograft (Ref: Ananthanarayan, 9th/e)