Which vitamin is essential for blood clotting in animals?

Vitamin K is essential for blood clotting in animals because it plays a critical role in the synthesis of proteins required for the coagulation process. These proteins, known as clotting factors, are necessary for the formation of blood clots that prevent excessive bleeding when injuries occur. Without adequate vitamin K, the body cannot produce these proteins effectively, leading to a higher risk of bleeding disorders.

Vitamin A, primarily associated with vision and immune function, does not have a direct role in coagulation. Similarly, vitamin C is important for collagen synthesis and immune function but is not involved in the blood clotting cascade. Vitamin E is an antioxidant that protects cell membranes but is not related to the clotting process. Thus, vitamin K is the only vitamin from the provided options that is directly involved in blood clotting mechanisms in animals.