The red colour to the red blood cells is due to the presence of

The correct option is C Haemoglobin

Hemoglobin (Hb or Hgb ) is an iron-containing protein present in erythrocytes or Red blood cells (RBC) of almost all vertebrates. Each hemoglobin is made up of 4 subunits, 2 alpha subunits and 2 beta subunits. Each subunit surrounds the central heme group that contains iron and binds to one oxygen molecule. The blood cells are red due to the interaction between iron and oxygen. Hence, the red colour of the red blood cells is due to the presence of haemoglobin.

So, the correct answer is 'Haemoglobin'.