Regarding Red Blood Cells / Erythrocytes - choose the correct option :

Question

( A ) A healthy individual has 12-16 gms of haemoglobin in every 100 ml of blood.
( B ) RBCs are devoid of nucleus in most of the mammals and are biconcave in shape.
( C ) RBCs are formed in the red bone marrow in the adults.
( D ) all of the above