Which of the following gives blood its reddish colour?
The subunits of haemoglobin
The correct option is D Oxygenated haemoglobin
Haemoglobin is a protein made of four subunits, each of which can carry one molecule of oxygen. Oxygenated haemoglobin gives blood the red colour, while deoxygenated haemoglobin gives it a bluish tinge, as can be seen in your veins.