[A] : lnsulin is not given orally.
[R]: Insulin is a macromolecule and is not absorbed by the mucosa layer.
a) If both A and R are true and R is the correct explanation of A
b) If both A and R are true but R is not the correct explanation of A
c) If A is true and R is false
d) If both A and R are false

Options

A. If both A and R are true and R is the correct explanation of A
B. If both A and R are true but R is not the correct explanation of A
C. If A is true and R is false
D. If both A and R are false

Answer

To solve the question, we need to evaluate the assertion (A) and the reason (R) provided:

**Assertion (A)**: Insulin is not given orally.
**Reason (R)**: Insulin is a macromolecule and is not absorbed by the mucosa layer.

### Step-by-Step Solution:

1. **Evaluate Assertion (A)**:
- Insulin is indeed not given orally. This is true because insulin is typically administered via injection. This is a well-established fact in medical practice, especially for individuals with diabetes.

2. **Evaluate Reason (R)**:
- Insulin is classified as a protein, which is a type of macromolecule. It is also true that macromolecules like proteins are generally not absorbed intact through the mucosal layer of the gastrointestinal tract. Instead, they are broken down into smaller peptides and amino acids by digestive enzymes.

3. **Determine the Relationship Between A and R**:
- While both A and R are true, the reason provided (R) does not fully explain why insulin is not given orally. The primary reason for not administering insulin orally is that digestive enzymes in the stomach would break down the insulin before it could be absorbed, not solely because it is a macromolecule.

4. **Conclusion**:
- Since both A and R are true, but R does not correctly explain A, the correct option is:
**b) If both A and R are true but R is not the correct explanation of A.**