​Inbred mouse strains with different MHC haplotypes (homozygous H-2ᵐ MHC haplotype and homozygous for the H-2ⁿ haplotype) were mated resulting in F1 progeny (H-2ᵐ/ⁿ). Skin transplantation experiments were performed between these mouse strains (parents with H-2ᵐ and H-2ⁿ MHC haplotype). Which one of the following statements about skin graft acceptance or rejection is correct?​

Correct option is D

Explanation-

Parents: One is homozygous for MHC haplotype H-2ᵐ, and the other for H-2ⁿ.
F1 progeny: Will be heterozygous, carrying both haplotypes → H-2ᵐ/ⁿ.

Concept of Skin Graft Rejection:
The immune system recognizes non-self MHC molecules as foreign and mounts an immune response against them. Grafts are accepted only if the MHC haplotypes match between donor and recipient.
Grafting:
        1.   Progeny → Parent:
          F1 (H-2ᵐ/ⁿ) → Parent (H-2ᵐ): The parent will reject the graft because the H-2ⁿ haplotype from the progeny is foreign to the parent.
                         F1 → Parent (H-2ⁿ): Same rejection happens due to the H-2ᵐ haplotype being foreign.

         2.   Parent → Progeny:
                H-2ᵐ → H-2ᵐ/ⁿ (Progeny): Graft is accepted, because the H-2ᵐ is already part of the progeny’s immune system.
                                  H-2ⁿ → H-2ᵐ/ⁿ: Also accepted, for the same reason.

Correct Interpretation:
Only parents can donate skin to the F1 progeny, but F1 cannot donate skin to either parent.

Correct Answer:
​Option D: "Skin graft from any of the parents will be accepted by the progeny recipient." 
Because F1 carries both haplotypes, so it will recognize grafts from either parent as self.