What Does the Westray Mine Disaster Illustrate

What does the Westray mine disaster illustrate?

A) the high level of safety standards in most Canadian mines
B) the need for workers to do more to look after their own safety in the workplace
C) a common pattern of employer neglect of workers' safety combined with lack of government enforcement of its own regulations
D) the fact that accidents will happen even if all parties work conscientiously for safer workplaces
E) the futility of unions' health and safety efforts