Explanation:

- The selling price of the pen is Rs660.

- It is mentioned that the profit is 20%.

- Profit is calculated on the cost price (CP). If SP = CP + Profit and SP = Rs660, we use the formula: Profit = Profit Percentage × Cost Price.

- Let CP be x. According to the problem: Selling Price = Cost Price + Profit = x + 0.2x = 1.2x.

- Therefore, 1.2x = 660. Solving for x: CP = 660 / 1.2 = Rs550.

- Profit = Selling Price - Cost Price = 660 - 550 = Rs110.

- Rs110 is labeled as Option 1. Thus, the nominal profit earned on the sale of the pen is Rs110.

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