Which of the following substances can bind to hemoglobin and reduce its oxygen-carrying capacity by forming a stable complex?

A Carbon monoxide ✓
B Nitric oxide
C Sulfur dioxide
D Hydrogen cyanide

Explanation

Carbon monoxide can bind to hemoglobin and reduce its oxygen-carrying capacity by forming a stable complex called carboxyhemoglobin.

Source

Guyton and Hall Textbook of Medical Physiology
Hematology Hematology: Hemoglobin and Oxygen Transport Hematology: Hemoglobin and Oxygen Transport Easy MEDICAL Confidence: high