Answer:
The correct answer would be "It binds to hemoglobin in red blood cells".
The carbon monoxide is tasteless, odorless, and colorless gas produced by burning fuel such as coal, gasoline, wood et cetera.
The affinity of hemoglobin to bind to the oxygen depends upon the concentration of oxygen and carbon dioxide in the blood.
At the time of carbon monoxide poisoning, the concentration of carbon monoxide is much more than that of oxygen.
It decreases the affinity of hemoglobin for oxygen and increases its affinity for carbon monoxide due to which most of the hemoglobin bind to the carbon monoxide instead of oxygen.
Consequently, enough oxygen cannot be transported to the cells.
