Final answer:
Set C will experience rapid graft rejection due to genetic differences and MHC incompatibility. Set B will experience slower rejection because of MHC-identity despite being genetically distinct. Set A will not have graft rejection due to genetic identity and matching MHC loci. Accordingly, based on the sets that were mentioned, the order of graft rejection would be C, B, and A, ranging from rapid to gradual to no rejection.
Step-by-step explanation:
In the given sets of experiments on skin transplantation in mice, we are considering the likelihood of graft rejection based on the genetic relatedness and Major Histocompatibility Complex (MHC) compatibility between the donor and the recipient.
In Set A, the skin has been grafted between genetically identical mice, or syngeneic graft, which means that the MHC loci are identical. Therefore, no rejection is expected here because the immune system of the recipient recognizes the graft as 'self'. In Set B, the skin was grafted between genetically unrelated mice, but the donor and recipient were MHC-identical (allograft). This set would most likely have a slower rejection because even though the mice are genetically different, having identical MHC may allow the recipient's immune system to tolerate the graft for a longer time, although it is likely they will eventually reject the graft and require immunosuppressant drugs. Finally, in Set C, the skin was grafted between mice that are genetically unrelated and have different MHC loci. Rapid rejection is expected in this set due to the recipient's immune system aggressively attacking the non-self MHC markers on the donor graft.
Therefore, the order of graft rejection from rapid, slow, to no rejection, based on the described sets, would be C, B, A.