Suppose a drop in the compensating wage differential between risky jobs and safe jobs has been observed. Two explanations have been put forward: a. Engineering advances have made it less costly to create a safe working environment. b. The phenomenal success of a new action serial 'Danger 999!' has imbued millions of viewers with a romantic perception of work-related risks. How can information on the number of workers employed in the risky occupation help determine which explanation is more plausible