This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
Most impoant antigen initiating graft rejection - 
Select and explain. 
A. HLA - Antigen, B. MHC - molecule, C. Polysaccharide, D. DHA
B: MHC - molecule
Answer: B: MHC - molecule 
Explanation: Reference :Robbins basic pathology 9th edition pg no 136 : the most impoant consequence of direct recognition is the activation of CD8+ T cells which recognise class I MHC molecules in the graft.Host CD4+ helper T cell may be triggered into proliferation and cytokine production by recognition of donor class II MHC molecules and drive an inflammatory response