Name the molecule that transports most of the carbon dioxide in the blood

It might be carbaminohemoglobin or just hemoglobin. Hemoglobin can bind to 4 molecules of carbon dioxide and transport them back to the lungs.

The answer to this is b

The answer to this will be from your lab notes/procedure. it would be best to ask another student who participated in the lab as we do not know what was done, what enzyme or if the temperature is celsius or fahrenheit. if i were to guess though i'd say the rate stopped due to enzyme denturing at high temperature