Economics studies choices that arise from one fact. What is that​ fact?
A. We are running out of clean air and clean waterWe are running out of clean air and clean water.
B. Not everyone considers the choices of othersNot everyone considers the choices of others.
C. Businesses create too many different brands of most goodsBusinesses create too many different brands of most goods.
D. Our resources are unable to satisfy all our wantsOur resources are unable to satisfy all our wants.