Let's assume the original price is $100.
Maria bought it at 20% discount: $100 - 20% = $80
Maria sold it with a 40% increase: $80 + 40% = $112
Profit = Selling price - Original price = $112 - $100 = $12
Percentage profit = (Profit / Original Price) x 100
= ($12 / $100) x 100 = 12%
The correct answer is 12%.