Trade-offs are required because demands are unlimited and resources are A. unlimited. B. economical. C. marginal. D. efficient D E. limited.

The correct answer is E. limited.<br /><br />Trade-offs are necessary because demands are unlimited, but resources are limited. This means that there are not enough resources to satisfy all the demands, and decisions must be made about how to allocate those resources most effectively. Trade-offs involve weighing the benefits and costs of different options and making choices that balance competing priorities.