P215 166

antonia

P215 166
Two experimental garden plots were each planted with the same number of tomato plants. Magnesium salts were added to the first plot but not to the second. The first plot produced 20 pounds and the second plot produced 10 pounds. Since nothing else but water was added to either plot, the higher yields in the first plot must have been due to the magnesium salts.
(A)        A small amount of the magnesium salts from the first plot leached into the second plot.
(E)The two experimental plots differed from each other with respect to soil texture and exposure to sunlight.
能帮我分析一下这道题吗？conclusion 和evidence各是什么？我选了E（正确答案），但我觉得A也可以，也可以使结论不成立。大家觉得呢？

linsonstudy

题目是问most seriously weaken，并不是A不可以，而是E比A更好。因为 A中 small amount 很可能不起什么作用。