A human in a closed environment with high amounts of carbon monoxide (CO) being released will experience which effect? A) Asthma-like symptoms and severe migraines B) Inflamed and upset the digestive system C) Prevention of oxygen from being transported in the body D) Production of chronic fatigue and irritate the nervous system

What this question is really testing

You need to know the main danger of carbon monoxide, which is not irritation of the lungs or stomach. The key issue is how CO affects the blood's ability to carry oxygen.

What carbon monoxide does in the bloodstream

Hemoglobin in red blood cells normally carries oxygen as $HbO_2$. Carbon monoxide competes for the same binding sites and forms carboxyhemoglobin:

$$Hb + CO \rightarrow HbCO$$

CO has a much higher affinity for hemoglobin than $O_2$, so even relatively small amounts can occupy hemoglobin and reduce oxygen delivery.

Why option C is correct

If hemoglobin is tied up as $HbCO$, less hemoglobin is available to carry oxygen. Tissues become oxygen-starved (hypoxia), which can lead to headaches, dizziness, confusion, and in severe cases loss of consciousness and death.

Why the other options are not the best match

• A: Headaches can happen, but “asthma-like symptoms” is not the main mechanism. CO poisoning is primarily a blood oxygen transport problem, not airway constriction.
• B: Digestive inflammation is not the hallmark effect of CO exposure.
• D: Fatigue can occur, but it is secondary to hypoxia, not the primary physiological effect being tested.

So, the best answer is C.