Which Finding Have Economists Who Study Labour Markets Discovered

Multiple Choice

Which finding have economists who study labour markets discovered

A) Chance is difficult to measure, but only about five percent of wage differences are related to chance.
B) Ability is not difficult to measure, but it is largely insignificant in explaining wage differences.
C) Work effort is difficult to measure, but it is not likely to contribute much to an explanation of wage differences.
D) Ability, effort, and chance are all likely to be significant contributors to wage differences.