Final answer:
Bones become bleached white when exposed to sunlight due to the damage to the pigment melanin in the skin.
Step-by-step explanation:
Bones become bleached white when exposed to sunlight. The ultraviolet (UV) radiation in sunlight can damage the pigment melanin in the skin, causing it to become lighter and reducing the amount of protection it provides against UV damage. This can result in bones appearing bleached or white due to the decreased pigmentation in the skin.