Answer
Option C - Before work starts and as needed
Explanation
An excavation is any man-made trench cut or hole which is made by digging the ground. It is one of the most hazardous constructional operations. If the excavation is 4 feet deep, the employees must be protected from a cave-in. So, the competent person which have enough experience and knowledge to assist must inspect the excavation before the work starts. May be at least once every day when the workers are doing work.
