A Study by Price Fishback and Shawn Kantor of the University

A study by Price Fishback and Shawn Kantor of the University of Arizona shows that after the passage of workers' compensation laws, wages received by workers in the coal and lumber industries fell.
Source: Price V.Fishback and Shawn Everett Kantor, "Did Workers Pay for the Passage of Workers' Compensation Laws?" Quarterly Journal of Economics, Vol.100, No.3, August 1995, pp.713-742.
Which of the following could explain why passage of workers' compensation laws led to a fall in wages in some industries?

A) The passage of the workers' compensation laws made it more expensive for firms to employ workers, thus reducing the demand for workers.
B) The passage of the workers' compensation laws allowed employers in hazardous industries to reduce compensating differentials which, in turn, reduce wages.
C) Employers reduced wages to partially offset the cost of having to purchase insurance that would compensate workers for injuries suffered on the job.
D) The supply of labour in these hazardous industries increased following the passage of the workers' compensation laws because jobs in these industries now pose less risk.