Which of the following is a trait shared by all public goods? A. A free- rider problem. B. Rivalry among consumers. C. The ability to exclude people. D. An elastic demand.

At work claire has a deadline that is rapidly approaching. as she works, she finds that she is doing more work in a shorter amount of time than usual. she thinks mor quickly, and her senses and memory are sharper. what is responsible for claire working more effectively?