In general, individuals and nations should specialize in producing goods __ other individuals or nations.

In general, individuals and nations should specialize in producing goods __ other individuals or nations.
A.for which they have a lower opportunity cost compared to
B.that they can produce more quickly than
C.that they can produce less quickly than
D.for which they have a higher opportunity cost compared to
正确答案：for which they have a lower opportunity cost compared to