Answer : (D) Vitamin K
Step 1 — Recall the function of vitamin K
Vitamin K is essential for the clotting (coagulation) of blood. It is required for the synthesis of prothrombin and other clotting factors in the liver.
Step 2 — Note the deficiency disease
A deficiency of vitamin K causes increased blood clotting time — even a small cut continues to bleed for a long time.
Step 3 — Check the other vitamins
| Vitamin | Main function | Deficiency disease |
|---|
| A | Vision, healthy epithelium | Night blindness, xerophthalmia |
| D | Calcium and phosphate metabolism | Rickets (children), osteomalacia (adults) |
| E | Antioxidant, protects cell membranes | Muscular weakness, sterility |
| K | Blood coagulation | Increased clotting time |
Step 4 — A useful pattern
All four of these — A, D, E and K — are the fat-soluble vitamins, so they are stored in the liver and adipose tissue and need not be supplied daily.
