**Core Concept**
An isograft is a type of transplant where the donor and recipient are genetically identical, typically involving the transplant of an organ or tissue from one individual to a genetically identical twin.

**Why the Correct Answer is Right**
In an isograft, the risk of rejection is minimized due to the genetic similarity between the donor and recipient. This is because the immune system of the recipient does not recognize the transplanted tissue as foreign, resulting in a reduced likelihood of an immune response. Isografts are often used in research settings to study the effects of transplantation on the immune system.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because an allograft, not an isograft, involves the transplant of an organ or tissue from one individual to another who is not genetically identical.

**Option B:** This option is incorrect because a xenograft involves the transplant of an organ or tissue from a different species, not just a genetically different individual.

**Option C:** This option is incorrect because an autograft involves the transplant of an organ or tissue from one part of the body to another in the same individual, not from one individual to a genetically identical twin.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that isografts have a lower risk of rejection compared to allografts, but they are still subject to other complications such as graft-versus-host disease.

**Correct Answer: C. Autograft**