**Question:** Vit K is available as all except -

A. Vitamin D
B. Calcium
C. Iron
D. Vitamin C

**Core Concept:**
Vitamin K is essential for the synthesis of coagulation factors (II, VII, IX, X, protein C, and protein S) in the liver through the process of gamma-carboxylation. Vitamin K is primarily obtained from dietary sources or synthesized in the gut flora.

**Why the Correct Answer is Right:**
Vitamin D, calcium, and iron are not classified as vitamins but rather as minerals. Vitamin D is needed for calcium absorption and bone health, calcium is crucial for blood clotting and nerve function, and iron is necessary for oxygen transport and storage.

**Why Each Wrong Option is Incorrect:**
Option A (Vitamin D) is incorrect because it is a mineral, not a vitamin. Vitamin K and Vitamin D serve different functions in the body.

Option B (Calcium) is incorrect because, although calcium is essential for blood clotting, it is not a vitamin but a mineral.

Option C (Iron) is incorrect because iron is involved in oxygen transport and storage rather than being a vitamin. These minerals serve distinct functions in the body.

Option D (Vitamin C) is incorrect because Vitamin C is crucial for collagen synthesis and immune function, while Vitamin K is vital for coagulation factors.

**Clinical Pearl:**
Understanding the correct roles of different vitamins, minerals, and their functions helps avoid confusion and misconceptions in clinical practice. This knowledge is crucial for diagnosing and treating patients with deficiencies or overdoses of these essential nutrients.