Variables X and Z in the table below are:

California voters and legislators frequently debate about the true cost of water in the course of trying to establish state policy to govern the use of water. The issue is confusing because

A) all water is ultimately a free gift of nature. B) the cost of water is infinite. C) water in itself, considered simply as a chemical compound, cannot be assigned any specific cost. D) we cannot settle a question that is entirely a matter of opinion.

A necessary condition for "perfect competition" is

A) price searchers. B) price takers. C) legal restrictions on entry into the market. D) a small number of huge firms. E) widespread and long-run economic profits.