Patient showed up at the ER with cherry-red mucous membranes, nail beds, and skin. These findings indicate:

A. Carbon monoxide poisoning
B. Aspirin overdose
C. Mosquito bite
D. Pneumonia

A is correct.

Cherry-red skin would indicate the patient has been exposed to carbon monoxide.

B is incorrect.

Aspirin overdose symptoms include nausea and vomiting. One would see pale skin with the patient.

C is incorrect.

Mosquito bite is localized and would not show signs of cherry-red mucous membranes.

D is incorrect.

Pneumonia would show respiratory signs, but not cherry-red mucous membranes.