This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Transplantation, Subject name: Surgery
Transplant of kidney from mother to son is an example of:- 
Select and explain. 
A. Autograft, B. Allograft, C. Isograft, D. Xenograft
B: Allograft
Answer: B: Allograft 
Explanation: Graft Autograft Isograft Homograft (Allograft) Heterograft (Xenograft) Tissue transplanted from one site to another on the same patient Transplant form a genetically identical donor, such as an identical twin Transplant from individual of same species Transplant from another species Xenograft Concordant Xenograft Discordant Xenograft Transplant between closely related species Example: For humans, old world monkeys & apes Advantage: Hyperacute rejections is not a threat Disadvantages: Zoonotic transfer of disease (Paicularly retroviral transmission) Transplant between distant related or divergent species Example: For humans, new- world monkeys & other mammals For physiological concern (organ size & availability) pigs are preferred animal donor Disadvantages: High risk of hyperacute rejection