Question

what is the cause of decubitus ulcers?
multiple choice
an allergenic agent irritates the skin.
pressure on bony projections for a prolonged period of time cuts off the blood supply to an area of skin, and an ulcer forms.
the skin is infected with mites that itch, and the scratching causes ulcers.
a tumor arises in the lower layers of the skin and opens up to the surface.
a caustic chemical such as an acid gets on the skin

Explanation:

Decubitus ulcers, also known as pressure ulcers or bedsores, are caused by prolonged pressure on bony prominences. This pressure cuts off the blood supply to an area of skin, leading to tissue damage and ulcer formation. Allergic agents typically cause rashes or allergic reactions, not decubitus ulcers. Skin infection with mites (like scabies) causes itching and lesions from scratching, but not the specific type of ulcer related to pressure. Tumors in the skin layers present differently (e.g., as abnormal growths). Caustic chemicals cause chemical burns, not decubitus ulcers.

Answer:

Pressure on bony projections for a prolonged period of time cuts off the blood supply to an area of skin, and an ulcer forms.