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: Unknown
All of the following are involved in graft vs host disease except 
Select and explain. 
A. Kidney, B. Liver, C. Stomach, D. Skin
A: Kidney
Answer: A: Kidney 
Explanation: GVHD characteristically involves liver, gastrointestinal tract and skin. It occurs as a complication of hematopoietic stem cell transplant when immunocompetent cells and precursors recognize host tissue alloantigens and react against them.