In One Week, Sami Can Knit 5 Sweaters or Bake

In one week, Sami can knit 5 sweaters or bake 240 cookies. In one week, Leila can knit 15 sweaters or bake 480 cookies. Sami's opportunity cost of knitting one sweater is _____

A) equal to 480 cookies.
B) equal to 240 cookies.
C) equal to 48 sweaters.
D) equal to 1/48 of a cookie.
E) equal to 48 cookies.