[A] : Steroid hormones are similar to cholesterol in structure.
[R]: Steroids contain phenanthrene ring structure.

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 analyze the given statements regarding steroid hormones and cholesterol, we can break down the solution into the following steps:

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that "steroid hormones are similar to cholesterol in structure." This is true because steroid hormones are indeed derived from cholesterol and share a similar structural framework.

**Hint**: Consider the relationship between steroid hormones and cholesterol. What do they have in common structurally?

2. **Understanding the Reason**: The reason states that "steroids contain a phenanthrene ring structure." This is also true. Steroid hormones possess a specific ring structure known as the phenanthrene ring, which is a characteristic feature of steroids.

**Hint**: Reflect on the structural components of steroids. What type of ring structure is commonly associated with them?

3. **Connecting Assertion and Reason**: Now we need to determine if the reason correctly explains the assertion. Since steroid hormones are derived from cholesterol and contain the phenanthrene ring structure, the reason does indeed provide a correct explanation for why steroid hormones are similar to cholesterol.

**Hint**: Think about how the structural features of one can explain the characteristics of the other. Does the presence of the phenanthrene ring clarify the similarity to cholesterol?

4. **Conclusion**: Both the assertion and reason are true, and the reason is the correct explanation of the assertion. Therefore, the correct answer is that both the assertion and reason are true, and the reason is the correct explanation of the assertion.

**Hint**: Evaluate the relationship between the two statements. Do they support each other logically?

### Final Answer:
Both assertion and reason are true, and the reason is the correct explanation of the assertion.