Recall the roles of the given vitamins

• Vitamin K: Helps in the synthesis of blood clotting factors. So it promotes blood clotting, not delays it.
• Vitamin C: Important for immunity, wound healing, and collagen synthesis.
• Vitamin E: Has an anti-clotting / anticoagulant effect in higher amounts and is known to help in delaying blood clotting.
• Vitamin B: A group of vitamins mainly involved in metabolism and nerve function.

Evaluate each option

• A: Vitamin K $\rightarrow$ Incorrect, because it supports clot formation.
• B: Vitamin C $\rightarrow$ Incorrect.
• C: Vitamin E $\rightarrow$ Correct, because it helps delay blood clotting.
• D: Vitamin B $\rightarrow$ Incorrect.

Final answer

The vitamin helpful in delaying blood clotting is: $\boxed{\text{Vitamin E}}$

Comparison with stored correct answer

• Stored correct answer: A (Vitamin K)
• Derived answer: C (Vitamin E)

These do not match. Vitamin K is actually essential for blood clotting, whereas Vitamin E is associated with delaying clotting.