The correct answer is (a). Vitamin K is essential for the production of prothrombin, a protein that is involved in blood clotting. In the absence of vitamin K, prothrombin levels decrease, which can lead to increased blood clotting time.
Vitamin D is important for bone health, but it does not play a role in blood clotting. Vitamin E is an antioxidant that can help protect cells from damage, but it does not play a role in blood clotting. Vitamin C is also an antioxidant, and it is involved in the production of collagen, a protein that is found in blood vessels. However, vitamin C does not play a direct role in blood clotting.
Blood clotting is a complex process that involves many different factors. Vitamin K is just one of the many factors that are necessary for blood clotting to occur properly. If vitamin K is not present, blood clotting time can increase, which can lead to bleeding problems.