Question

cattle contribute directly to topsoil loss by trampling the ground over and over again. the soil they tramp down becomes compacted hard, especially if there is clay in it. then, when it rains, this compacted soil is less able to absorb water, so the water simply runs off, taking the top layer of soil with it. cattle also eat all the perennial grasses (grasses that normally come back year after year), and this allows weeds and tougher shrubs to spread. the new weeds do not anchor the topsoil as well as the grasses, so wind and rain can take it away easily. cattle create topsoil ______.

• abundance
• instability
• perfection

Explanation:

The passage describes how cattle cause topsoil loss: they compact the soil (reducing water absorption, leading to runoff), eat perennial grasses (allowing weeds that don't anchor soil well to spread), and wind/rain can then take the topsoil. "Instability" fits as the topsoil becomes prone to being carried away (not stable). "Abundance" is incorrect (cattle cause loss, not more topsoil). "Perfection" is illogical (topsoil is damaged, not made perfect).

Answer:

B. instability