Explanation:

The Workmen's Compensation Act, 1923 was made to offer compensation to the workers who have encountered injuries due to an accident during their employment. This act ensures that rights of the laborers are maintained even after they encounter some disability or death due to an accident during their work.

• Personal injury under the Act means physiological injury. It is a bodily injury or a physical injury to which would also include abnormal mental conditions. Personal injury includes any harmful change in the body. 

Hence option 4th is correct.