Which among the following is not found in the red blood corpuscles of human beings?

The red color is imparted to blood by the pigment called hemoglobin. Hemoglobin is rich in iron, and it helps in the transfer of oxygen in the body. The red blood cells have a disc-like shape, and they are inflated from the center. This shape is achieved because of the lack of a nucleus in them. 

Hence, the correct option is C.