Solution: The price of milk is increased by 20%.

Let the original price of milk per liter be $10.

Increased price: \(\frac{120}{100}\) * $10 = $12[/m]

Number of liters of milk: \(\frac{Total\ price\ }{price\ per\ litre}\)

Number of liters of milk before increase: \(\frac{60}{10}\)=6

Number of liters of milk after increase: \(\frac{60}{12}\)=5

The difference in the quantity of milk obtained: 6 - 5 = 1

Thus, for the $10 initial price, the difference is 1 liter.

For 5 liters difference, \(\frac{10}{5}\) = $2

Therefore, A is the correct answer.

Answer A