Final answer:
Carbon monoxide poisoning presents with symptoms like headache and confusion and can cause 'cherry red skin,' while methemoglobinemia results in 'chocolate-brown blood' and symptoms such as cyanosis.
Step-by-step explanation:
Comparing carbon monoxide poisoning and methemoglobinemia, the symptoms and presentations are distinct due to the different mechanisms by which they affect oxygen transport in the blood. Carbon monoxide poisoning typically presents with symptoms that can include headache, dizziness, weakness, vomiting, chest pain, and confusion, and it is characterized by the classically described but rare “cherry red skin” due to the carboxyhemoglobin that forms when carbon monoxide binds with hemoglobin, preventing it from transporting oxygen. In contrast, methemoglobinemia, which involves the oxidation of hemoglobin iron from the ferrous (Fe²+) to ferric (Fe³+) state, prevents oxygen binding and results in a “dark chocolate-brown” coloration of the blood. Symptoms can include cyanosis (bluish skin due to lack of oxygen) and dyspnea. The correct answer to the question is: a) Carbon monoxide poisoning: Cherry-red skin; Methemoglobinemia: Chocolate-brown blood.