Answer: B the weight of the cattle compacts the soil
Step-by-step explanation:
ecosystem related would mean that the answer relates to the land. this rules out A and D as they are related to profits off of the land and not necessarily the health/wellbeing of the physical land. C is also out-ruled as the price of the cattle is not a directly going to negatively effect the land.
The weight for the cattle is very relevant as cattle are very heavy and with regular walking/grazing/standing on the rangeland the soil will become harder (aka. compact) resulting in less loose soil for grass to grow.
This can be off set by allowing the land to rest or other means such as plowing occasionally so that it is easier for grass to continue to thrive for feeding the cattle.