Concept:Blood is made up of plasma and formed elements, which include red blood cells, white blood cells, and platelets. Hormones are not major components of blood itself; they are transported in plasma.
Explanation:Platelets (II) are cell fragments needed for clotting.
Plasma (III) is the liquid part of blood.
White blood cells (IV) fight infections.
Hormones (I) are chemical messengers, not major structural components of blood.
Therefore, the correct combination is II, III and IV.
Answer:D. II, III and IV only