Which of the following is/are the better buy(s)?

Which of the following is/are the better buy(s)?
There may be more than one correct answer.
☐ 3 liters of milk at $5.73.
☐ 3.5 liters of milk at $6.09.
☐ 5 liters of milk at $9.75.
☐ 7 liters of milk at $12.18.
☐ 2.5 liters of milk at $4.90.