What is a visible effect of radiation exposure characterized by a sunburn-like appearance?

Erythema is a visible effect of radiation exposure characterized by a sunburn-like appearance on the skin. This condition occurs due to the inflammation of the skin's blood vessels following radiation exposure, which leads to increased blood flow and redness. The appearance of erythema is often an early sign of skin damage, indicating that the skin has been exposed to a certain threshold of radiation.

In contrast, moist desquamation refers to the peeling or shedding of the skin that can occur after severe radiation exposure, which is more advanced than erythema and typically occurs after noticeable damage has already manifested. Bone Marrow Syndrome and Gastrointestinal Syndrome are serious and potentially life-threatening conditions resulting from high doses of radiation, leading to damage in the respective systems, but they do not present as visible skin changes like erythema does. Thus, erythema is specifically identified by its sunburn-like appearance, making it the correct answer.