The correct answer is option 3, Vitamin K. Vitamin K is necessary for blood clotting. Blood clotting is a complex process that prevents excessive bleeding when a blood vessel is injured. Vitamin K helps in the production of proteins that are important for blood clotting. These proteins are responsible for the formation of blood clots, which plug the damaged blood vessel and stop the bleeding.

Let`s dissect the other options to understand why they are not the correct answer:

Option 1, Vitamin A, is important for vision, immune function, and healthy skin, but it is not directly involved in the blood clotting process.

Option 2, Vitamin D, is important for bone health, immune function, and calcium absorption, but it is not directly involved in the blood clotting process.

Option 4, Vitamin C, is necessary for the synthesis of collagen, a protein important for skin, tendons, and blood vessels. While it is involved in the healing of wounds, it is not directly involved in blood clotting.

Therefore, the correct answer is option 3, Vitamin K, as it plays a crucial role in the blood clotting process.