**Core Concept**
Vitamin K plays a crucial role in blood coagulation by serving as a cofactor for the enzyme gamma-glutamyl carboxylase, which activates various clotting factors in the liver. This activation is essential for the proper function of the coagulation cascade.

**Why the Correct Answer is Right**
The correct answer is related to the level of a specific clotting factor in vitamin K deficiency. Vitamin K is necessary for the carboxylation of glutamic acid residues in the N-terminal region of certain clotting factors, such as prothrombin (factor II), factors VII, IX, and X. Without vitamin K, these factors remain in an inactive, uncarboxylated form. Therefore, the level of these factors is decreased in vitamin K deficiency.

**Why Each Wrong Option is Incorrect**
**Option A:** This option may be tempting, but it is not the correct answer because the level of a specific clotting factor would indeed be altered in vitamin K deficiency.

**Option B:** This option is incorrect because the correct answer is related to a specific factor, not a general statement about vitamin K levels.

**Option D:** This option is not relevant to the question and does not directly relate to the effects of vitamin K deficiency on clotting factors.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that vitamin K deficiency can lead to a decrease in the levels of clotting factors II, VII, IX, and X, which can result in a prolonged prothrombin time (PT) and partial thromboplastin time (PTT).

**Correct Answer:** C.