**Core Concept**
Skin grafting involves transferring skin from one part of the body to another or from one individual to another. The type of grafting depends on the source of the skin used. In this case, the skin is taken from the twin brother, making it genetically identical.

**Why the Correct Answer is Right**
An isograft is a type of graft that involves transplanting tissue from one individual to another who is genetically identical, such as twins. This is because twins share the same genetic makeup, making the transplanted tissue less likely to be rejected by the immune system. In this scenario, the skin grafting done on the wound using skin taken from the twin brother is an example of an isograft.

**Why Each Wrong Option is Incorrect**
**Option B:** An allograft is a type of graft that involves transplanting tissue from one individual to another who is not genetically identical. This type of graft is more likely to be rejected by the immune system, making it a less suitable option for this scenario.
**Option C:** An autograft is a type of graft that involves transplanting tissue from one part of the body to another in the same individual. This is not applicable in this scenario, as the skin is taken from the twin brother, not from the same individual.
**Option D:** A xenograft is a type of graft that involves transplanting tissue from one species to another. For example, a pig's skin is used to create a xenograft for humans. This is not applicable in this scenario, as the skin is taken from a human (the twin brother).

**Clinical Pearl / High-Yield Fact**
It's essential to note that isografts are less likely to be rejected by the immune system due to the genetic similarity between the donor and recipient. However, other factors such as the size of the graft, the presence of any underlying medical conditions, and the overall health of the recipient can still affect the success of the graft.

**✓ Correct Answer: A. Isograft**