Explanation:

- Under perfect competition, Price = AR = MR. This means prices are constant across different levels of output.

- The marginal revenue (MR) curve is not below the average revenue (AR) curve. They coincide because each additional unit sold adds the market price to the total revenue, and that price is constant.

- Average Revenue (AR) remains constant because firms are price takers and cannot influence market price.

- In summary, under perfect competition:

- Price = AR = MR, and

- AR remains constant.

Correct Answer: Option 4, both (b) and (c).

.