The prevention of accidents makes it necessary not only for safety devices to be used to guard expose machinery, but also the machines be instructed in the safety rules they must follow for their own protection and that the lighting in the plant be adequate. The paragraph best supports the statement that industrial accidents:
1) are caused by inadequate lighting in the plant
2) can be prevented by using safety devices
3) can be prevented by instructing machines in safety rules
4) are caused by exposed machinery