.....A…... ( a part of a alimentary canal ) secretes .....B…... (an enzyme) which converts trypsinogen into trypsin.

Options

A. `{:(A,B),("Small intestine","Trypsinase"):}`
B. `{:(A,B),("Small intestine","Intestinal Lipase "):}`
C. `{:(A,B),("Intestinal mucosa","Enterokinse"):}`
D. `{:(A,B),("Small Intestine","Steapsin"):}`

Answer

To solve the question, we need to identify the part of the alimentary canal that secretes an enzyme responsible for converting trypsinogen into trypsin.

### Step-by-Step Solution:

1. **Identify the Enzyme and Its Function**: The enzyme that converts trypsinogen into trypsin is known as enterokinase (also called enteropeptidase).

2. **Identify the Source of the Enzyme**: Enterokinase is secreted by the intestinal mucosa, which is a part of the small intestine.

3. **Match the Options**: We need to check the options provided in the question:
- Option 1: A is small intestine, B is trypsinase (Incorrect, as trypsinase is not the enzyme that converts trypsinogen).
- Option 2: A is small intestine, B is intestinal lipase (Incorrect, as intestinal lipase is not involved in converting trypsinogen).
- Option 3: A is intestinal mucosa, B is enterokinase (Correct, as enterokinase is secreted by the intestinal mucosa and converts trypsinogen to trypsin).
- Option 4: A is small test line, B is distance (Incorrect and irrelevant).

4. **Conclusion**: The correct answer is Option 3, where A is the intestinal mucosa and B is enterokinase.

### Final Answer:
A (intestinal mucosa) secretes B (enterokinase), which converts trypsinogen into trypsin.

---