How does carbon monoxide interfere with your body's ability to deliver oxygen to cells?

Carbon monoxide inhibits the blood's ability to carry oxygen to body tissues including vital organs such as the heart and the brain. When Carbon dioxide is inhaled, it combines with the oxygen carrying hemoglobin of the blood to form carboxyhemoglobin. Once combined with the hemoglobin, that hemoglobin is no longer available for transporting oxygen. The carboxyhemoglobin build up is based on the concentration of the gas being inhaled and the duration of the exposure. 

The correct answer is c