Assertion: Insulin forms hormone receptor complex which regulate gene expression.
Reason: Insulin is a peptide hormone which can easily pass cell membrane to interact with hormone-receptor complex.

Options

A. (a) Both, Assertion and Reason, are true and Reason is the correct explanation of Assertion
B. (b) Both, Assertion and Reason, are true but Reason is not the correct explanation of Assertion
C. (c) If Assertion is true but Reason is false
D. (d) If Assertion is false but Reason is true

Explanation

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that "Insulin forms hormone receptor complex which regulates gene expression." This is true. Insulin, when it binds to its specific receptor on the cell membrane, forms a hormone-receptor complex that can influence gene expression through various signaling pathways.

2. **Understanding the Reason**: The reason provided is "Insulin is a peptide hormone which can easily pass cell membrane to interact with hormone-receptor complex." This statement is misleading. While it is true that insulin is a peptide hormone, it does not easily pass through the cell membrane due to its hydrophilic nature.

3. **Analyzing the Mechanism**: Insulin is a water-soluble (hydrophilic) hormone, which means it cannot cross the lipid bilayer of the cell membrane. Instead, it binds to specific receptors located on the plasma membrane of target cells. This binding activates intracellular signaling pathways, leading to various cellular responses, including the regulation of gene expression.

4. **Conclusion on Assertion and Reason**: Since the assertion is correct (insulin does form a hormone-receptor complex that regulates gene expression), but the reason is incorrect (insulin does not easily pass through the cell membrane), we conclude that the correct relationship is that the assertion is true, but the reason is false.

5. **Final Answer**: Therefore, the correct option is C: "Assertion is correct but reason is incorrect."