The correct answer is actually C. The trench is more than 4 feet deep and the devices must be within 25 feet of all workers.
In archaeology, when it comes to excavations and creating trenches in order to find various artifacts from distant past, there are certain rules to be followed in order to ensure the safety of the archaeologists. One of those rules refers to the importance of ramps, ladders, or stairways to enable the workers and archaeologists a means of egress (or escape, in other words).
In case something bad happens, those people need to get out of the trench as soon as possible via the means of egress (ramps, etc). However, there are some requirements - the trench needs to be more than 4 feet deep, and those devices cannot be near the workers (there has to be a distance of at least 25 feet between them).
