Why are demand curves downward sloping?

A short-run depreciation of the British pound would be consistent with:

a. a temporary fall in the British money supply. b. a temporary fall in the European money supply. c. a temporary rise in the European money supply. d. either a temporary fall in the British money supply

All of the following are reasons average workers in the United States today produce more than their counterparts a century ago EXCEPT that the modern worker:

A. is better educated. B. has more physical capital to work with. C. has better technology to work with. D. works longer hours.