Which one of the following statements regarding haemoglobin is

Which one of the following statements regarding haemoglobin is correct?

Haemoglobin present in RBC can carry only oxygen but not carbon dioxide.
Haemoglobin of RBC can carry both oxygen and carbon dioxide.
Haemoglobin of RBC can carry only carbon dioxide.
Haemoglobin is only used for blood clotting and not for carrying gases.
This question was previously asked in
UPSC CDS-1 – 2019
The correct answer is B. Haemoglobin is the protein molecule in red blood cells responsible for transporting oxygen from the lungs to the body’s tissues. While its primary function is oxygen transport, haemoglobin also binds to and transports a small percentage (about 20-25%) of carbon dioxide from the tissues back to the lungs. The majority of carbon dioxide is transported in the blood plasma as bicarbonate ions.
Haemoglobin in RBCs can bind and transport both oxygen and a portion of carbon dioxide.
Oxygen binds to the heme group (iron-containing part) of haemoglobin, forming oxyhaemoglobin. Carbon dioxide binds to the amino groups of the globin protein part of haemoglobin, forming carbaminohemoglobin. The binding of oxygen and carbon dioxide are influenced by factors such as pH, temperature, and the concentration of other molecules like 2,3-bisphosphoglycerate (2,3-BPG).