Which of the following factors is known as Chirstmas factor ?

Options

A. Factor `VIII`
B. Factor `XII`
C. Factor `IV`
D. Factor `IX`

Explanation

To determine which factor is known as the Christmas factor, we can follow these steps:

### Step 1: Understand the Context
The term "Christmas factor" is associated with a specific blood coagulation factor. It is important to know that this term is linked to a genetic disorder related to blood clotting.

### Step 2: Identify the Condition
The Christmas factor is related to a condition known as Hemophilia B. This condition is characterized by a deficiency in a specific clotting factor, which leads to problems with blood coagulation.

### Step 3: Know the Specific Factor
Hemophilia B is caused by a deficiency in Factor IX (Factor 9). This is the key factor that is referred to as the Christmas factor.

### Step 4: Review the Options
Now, let’s review the options provided:
1. Factor 8
2. Factor 12
3. Factor 4
4. Factor 9

### Step 5: Eliminate Incorrect Options
- Factor 8 is associated with Hemophilia A, not B.
- Factor 12 is not related to Christmas disease.
- Factor 4 is not known as the Christmas factor.

### Step 6: Confirm the Correct Answer
The only factor that corresponds to the Christmas factor is Factor 9. Therefore, the correct answer is:

**Factor 9 (Option 4)**

### Final Answer
The Christmas factor is **Factor 9**.

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