Whether Studying the Size of the Canadian Economy or the Number

Whether studying the size of the Canadian economy or the number of children a couple will choose to have,the unifying concept is

A) wants are limited,resources are limited,and thus trade-offs must be made.
B) wants are unlimited,resources are limited,and thus trade-offs must be made.
C) wants are unlimited,resources are limited to some but not to others,and thus some people must make trade-offs.
D) wants are unlimited,resources are unlimited,and thus no trade-offs need to be made.
E) wants are unlimited,resources are limited,and thus government needs to do more.