Tonics made out of the liver are very effective in curing haemopoietic disorder because

Options

A. They contain proteins
B. They contain `RBC_s`
C. They contain bile juice
D. They contain vitaniin `B_12`

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks why tonics made from the liver are effective in curing hematopoietic disorders. Hematopoietic disorders are conditions that affect blood cell production.

2. **Identifying the Options**: The options provided are:
- A) They contain protein
- B) They contain RBCs
- C) They contain bile juice
- D) They contain vitamin B12

3. **Analyzing Each Option**:
- **Option A (They contain protein)**: While proteins are important for overall health and cell function, they are not specifically linked to the treatment of hematopoietic disorders.
- **Option B (They contain RBCs)**: Tonics cannot contain red blood cells (RBCs) as they are not a component that can be extracted in a tonic form.
- **Option C (They contain bile juice)**: Bile juice is produced by the liver but is primarily involved in digestion, not in the production of blood cells.
- **Option D (They contain vitamin B12)**: The liver is rich in vitamin B12, which is essential for the production of red blood cells and the proper functioning of the nervous system. A deficiency in vitamin B12 can lead to anemia and other hematopoietic disorders.

4. **Conclusion**: Based on the analysis, the correct answer is **Option D (They contain vitamin B12)**. Tonics made from the liver are effective in curing hematopoietic disorders because they are rich in vitamin B12, which is crucial for the formation of red blood cells.