Which vitamin helps in blood clotting in the human body?

Vitamin K is the fat-soluble vitamin essential for blood clotting. The liver uses it as a cofactor to produce active clotting factors II (prothrombin), VII, IX and X. Without enough Vitamin K, these factors cannot be made, leading to prolonged bleeding. Vitamin D supports calcium balance and bone health, Vitamin E acts as an antioxidant, and Vitamin C supports collagen and immunity — none of them produce clotting factors. Hence the correct answer is Vitamin K.