Final answer:
The true statement is that landslides can indeed travel up an opposing slope after descending into a valley due to the accumulation of kinetic energy, though they will not reach the same height as where they initiated.
Step-by-step explanation:
The statement that sometimes landslides can come down into a valley and then race upslope on the opposite side is True. When landslides occur, they can display complex dynamics depending on the terrain and material involved. For example, when a landslide comes barreling down a hillside, it has a considerable amount of kinetic energy. Upon reaching the bottom of the valley, some of this energy can propel the debris up an opposing slope, but not to the original height from which it fell, partly because energy is lost due to friction. Tree roots and vegetation play a crucial role in stabilizing hillsides and can help to prevent landslides by holding the soil in place, indicating the importance of vegetation management in landslide-prone areas.