Just as HCI is for the pepsinogen, so is the
(a) bile juice for fats
(b) glucagon for glucose
(c) haemoglobin to oxygen
(d) enterokinase for trypsinogen

Options

A. bile juice for fats
B. glucagon for glucose
C. haemoglobin to oxygen
D. enterokinase for trypsinogen

Explanation

To solve the question, we need to identify the relationship between HCl and pepsinogen and then find a similar relationship among the given options.

1. **Understanding the Relationship**: HCl (hydrochloric acid) is produced in the stomach and is essential for converting pepsinogen, an inactive enzyme (proenzyme), into its active form, pepsin. This relationship is crucial because pepsin is responsible for digesting proteins.

2. **Analyzing Each Option**:
- **Option A: Bile juice for fats**: Bile juice aids in the emulsification of fats, which is important for fat digestion, but it does not activate any proenzyme. Therefore, this option does not match the relationship we are looking for.

- **Option B: Glucagon for glucose**: Glucagon is a hormone that raises blood glucose levels but does not activate any proenzyme. Thus, this option is also not correct.

- **Option C: Hemoglobin to oxygen**: Hemoglobin binds oxygen for transport in the blood but does not involve the activation of any proenzyme. Hence, this option is not the correct analogy.

- **Option D: Enterokinase for trypsinogen**: Enterokinase (also known as enteropeptidase) is an enzyme that activates trypsinogen (a proenzyme) into its active form, trypsin. This is a direct analogy to how HCl activates pepsinogen into pepsin.

3. **Conclusion**: The correct answer is **Option D: Enterokinase for trypsinogen** because it mirrors the relationship of HCl activating pepsinogen.

### Summary of Steps:
1. Identify the relationship between HCl and pepsinogen.
2. Analyze each option to see if it reflects a similar relationship.
3. Conclude that Option D is the correct answer.