Final answer:
Oxygen is transported in the blood as oxyhemoglobin, a complex where oxygen is bound to hemoglobin in red blood cells. Carbonic anhydrase is involved in the carbon dioxide transport system as bicarbonate ions but not in direct oxygen transport.
Step-by-step explanation:
Oxygen is transported in the blood primarily as oxyhemoglobin, which is a complex formed when oxygen binds to the hemoglobin in red blood cells. The correct answer to the student's question, 'Oxygen is transported in the blood as ________,' is B) oxyhemoglobin. While carbon dioxide is also transported in the blood, it mostly does so in the form of bicarbonate ions after a reaction facilitated by the enzyme carbonic anhydrase, forming carbonic acid that subsequently dissociates into bicarbonate and hydrogen ions. It is important to note that while carbonic anhydrase plays a crucial role in carbon dioxide transport, it does not directly transport oxygen.