In Wage-Job Safety Space, Workers' Indifference (Or Isoutility) Curves Slope

In wage-job safety space, workers' indifference (or isoutility) curves slope downwards because:

A) Workers require a higher compensating wage in order to avoid risky jobs.
B) Workers require a higher compensating wage in order to remain indifferent to the additional risk.
C) Lower wages are required in order to keep profits constant if a higher degree of job safety is required.
D) Employers will compensate them for their aversion to risk.
E) More hours of labour are supplied when wages are increased.