What would make a hill slope more stable? select one: a. highway construction across the slide, which creates continuous, steep slopes that are cut into the hillside alongside the new road. b. enabling ongoing or intermittent erosion of debris that occupies the toe of the landslide, either by a stream or ocean waves or land use. c. terracing a landslide to create flat areas for gardening or agriculture that are separated by steep slopes and irrigated regularly. d. redirecting surface water flow so that it travels around and away from the landslide and covering the landslide with a water impermeable membrane. e. residential development on the body of a landslide, where each home is built on an artificially leveled surface and above the homes are steep slopes near the crown of the slide.

d. Redirecting surface water flow so that it travels around and away from the landslide and covering the landslide with a water impermeable membrane.

Explanation:

Slopes are created when erosion acts on uplifts formed during tectonic processes. The angle, physical qualities of the materials found on the slope, and the activities carried out on the slope will determine its stability.  

Some activities which threaten a slope’s stability include introducing heavy weights on the sides of a slope and exposure to water which affects the structural integrity of the rocks  on the slope. This is why a highway construction, residential development and enabling intermittent erosion are bad ideas for bolstering the stability of a slope.

While the presence of vegetation on a slope makes it more stable, removal of present vegetation and irrigation will weaken the structure of a slope.