- A Chlorophyll
- B Hemocyanin
- C Myoglobin
- D Hemoglobin
Correct answer: D. Hemoglobin
Explanation: Hemoglobin, present in RBCs, binds and transports most of the O2 in blood. Each molecule can carry up to four O2 molecules.
Concept context
The mechanics of breathing, lung volumes, gas transport in blood, the Bohr effect, and respiratory regulation.