Explanation:

- The selling price of the plate is 140% of the cost price. This means the selling price is 1.4 times the cost price.

- Profit is calculated as the difference between selling price and cost price.

- To find the profit percentage, divide the profit by the cost price and multiply by 100.

- If the cost price is considered as 100 units, the selling price would be 140 units.

- Profit is 140 - 100 = 40 units.

- Profit percentage = (Profit / Cost Price) * 100 = (40/100) * 100 = 40%.

Option 3: 40%