The correct option is D Serum = plasma - clotting factors
Plasma is the straw coloured fluid found in blood. About 90% of plasma contains water and the rest is made up of proteins, ions and other minerals.
Plasma without the clotting factors is called serum. Several substances along with fibrinogen helps in clotting of blood. So serum is similar in composition to plasma but lacks clotting factors that are involved in the coagulation of blood.
Hence, serum = plasma - clotting factors.