Compensatory wage gap: refers to the wage difference caused by the non-monetary characteristics of different jobs. According to the definition above, which of the following options has nothing to do with compensatory wages? ["The annual income of a city's power system meter reader is higher than the city's per capita salary. The high salary is used to compensate for their physical and mental labor consumed during the work process.", 'Coal workers receive higher wages than other workers with similar education levels. High wages are used to compensate for the dullness and danger of coal mining and the long-term health problems faced by coal workers.', "Professor's salary is lower than lawyers and doctors who have about the same education time, and low salary can be compensated by academic and personal satisfaction brought by work.", 'Night workers in factories pay more than workers in the day shift. High wages are used to compensate for the adverse health effects of having to work at night and sleeping during the day.']