boldface 6

6. Plants that exhibit certain leaf diseases tend to measure extremely high in the amount of zinc in their leaf and stem tissue. Botanists have discovered that phosphorus of the type typically used in a phosphorus-high fertilizer reacts with the zinc in such a way as to prevent treated plants from exhibiting the leaf diseases, and zinc is the cause and not merely an effect of the leaf diseases. Thus, plants can be cured from these leaf diseases by the use of a fertilizer high in phosphorus.

The two portions in boldface play which of the following roles?

(A) The first is the first-premise that the argument includes; the second is the second-premise that is in support of this argument.

(B) The first is the background that the argument includes; the second is the part of evidence in support of this argument.

(C) The first is the first-premise that the argument includes; the second is the consideration that is in support of the first.

(D) The first is the premise that supports the evidence; the second is that evidence.

(E) The first is the first-premise that the argument includes; the second is the second-premise that is complementary to other evidence.

the answer is B. But I think A or E is more right. Because the first is a premise, if the first doesn't stand, meaning if Plants that exhibit certain leaf diseases do not tend to measure high in the amount of zinc in their leaf and stem tissue, even if zinc is the cause, the disease won't be cured by lower the zinc since the sick plants do not contain more than the normal level zinc.