Typical silt loam soil is comprised of approximately 50 percent soil p

­A supposition is a conjecture about a fact. Our point of view is not necessarily true in reality.

The first bold part is a fact, explaining a scenario. The second part discusses what the farmers should do to avoid such consequences.

So among the answer choices best is D. The first bold is a middle ground conclusion about the soil

 

This one doesn't work. There isn't even one conclusion, let alone two. For a statement in a CR argument to be a conclusion, it must be an opinion based on one or more premises in the argument. As Haffun pointed out, no premise is given to support the first bold, so it isn't a conclusion. It is presented as factual information with no basis within the argument, and in such cases we accept the given information as a premise.

As for the second bold, while it does seem to follow to some extent from what came before, it isn't really presented as a conclusion. First, it is presented as general advice that is given to farmers ("farmers are advised") rather than the opinion of the author (or any other particular party). Second, it isn't really building on the premises. They are almost entirely about what soil compaction is and why it's bad, while the second bold is providing advice about how to avoid compaction. While it's true that conclusions don't usually build perfectly on premises (that's where assumptions come in), this is too loosely connected to be a conclusion at all. Also, Role questions don't usually present arguments with clear flaws, since we aren't looking for assumptions in these cases.

In short, there's no valid answer here. B starts off well, but we'd need it to say that the second details potential solutions.