The case of winter roses offers an excellent example of the seasons why international trade can be beneficial. Consider first how hard it is to supply American sweethearts with fresh roses in February. The flowers much be grown in heated greenhouses, at great expense in terms of energy, capital investment, and other scarce resources. Those resources could have been used to produce other goods. Inevitably, there is a trade-off. In order to produce winter roses, the U.S. economy much produce less of other things, such as computers. Economists use the team opportunity cost to describe such trade-off: the opportunity cost of roses in term of computers is the number of computers that could have been produced with the resources used to produce a given number of roses.