Identify the population and the sample.

a. A survey of 1000 U.S. adults found that 83% think credit cards tempt people to buy things they cannot afford.
b. Thirty-eight nurses working in the San Francisco area were surveyed concerning their opinionsof managed health care.
c. A survey of 39 credit cards found that the average annual percentage rate (APR) is 12.83%.
d. A survey of 1205 physicians found that about 60% had considered leaving the practice ofmedicine because they were discouraged over the state of U.S. health care.