What is the general rule for sloping trenches?

The correct choice emphasizes safety by stipulating that trenches should not be steeper than a one and one-half horizontal to vertical ratio. This guideline is critical because steeper slopes can significantly increase the risk of cave-ins, which pose a serious hazard to workers in or near the trench. By maintaining a more gradual slope, the structural integrity of the soil is better preserved, reducing the likelihood of collapses and enhancing the overall safety of the excavation site.

The other options suggest either a less safe angle or more extreme ratios that could compromise safety without appropriately accounting for soil type and weather conditions, which play a significant role in determining how steep a trench can be. Therefore, adhering to a slope of one and one-half horizontal to vertical is a well-established guideline in trench safety regulations.