A gardener plants a 60-square-foot vegetable garden with carrot seeds and lettuce seeds. In each square foot of the
garden, he plants either 6 carrot seeds or 2 lettuce seeds.
If he plants two-thirds of the area of the garden with
carrot seeds, and the remaining area with lettuce seeds,
what is the ratio of lettuce seeds to carrot seeds?
(A) 6:1
(B) 1:2
(C) 13
(D) 1:6