Christmas disease is caused due to absence of

Options

A. Plasma thromboplastin
B. Plasma thromboplastin anticedent
C. Anti-haemoglobin
D. Factor-IX

Answer

**Step-by-Step Solution:**

1. **Understand the Question**: The question asks about the cause of Christmas disease, which is a specific medical condition.

2. **Identify Christmas Disease**: Recognize that Christmas disease is also known as hemophilia B. This is a genetic disorder related to blood clotting.

3. **Research the Cause**: Christmas disease is caused by the absence or defect of a specific clotting factor. In this case, it is associated with Factor 9.

4. **Evaluate the Options**: The question provides four options:
- Plasma thrombo-plastin
- Plasma thrombo-plastin (repeated option)
- Anti-sedent
- Anti-hemoglobin
- Factor 9

5. **Select the Correct Answer**: Since Christmas disease is specifically linked to the absence of Factor 9, the correct answer is **Factor 9**.

6. **Conclusion**: Thus, the absence of Factor 9 is what causes Christmas disease.

**Final Answer**: Christmas disease is caused due to the absence of **Factor 9**.

---