请教GWD1-Q30和Q40

Q30:

The quality of unrefined olive oil is not actually defined in terms of acidity, yet extensive tests have shown that the less free oleic acid an unrefined olive oil contains per liter, the higher its quality.  The proportion of free oleic acid that an olive oil contains is an accurate measure of the oil’s acidity.

If the statements above are all true, which of the following conclusions is best supported by them ?

1. When an olive oil is refined, the concentration of oleic acid in the oil is reduced.
2. The quality of an unrefined olive oil can be determined only by accurately measuring its acidity.
3. If an unrefined olive oil is intermediate in acidity between two other unrefined olive oils, it will also be intermediate between them in quality.
4. Free oleic acid is the only acid that unrefined olive oil contains.
5. People who judge the quality of unrefined olive oils actually judge those oils by their acidity, which the judges can taste.

   Answer:

在A、C、E犹豫，请大侠帮忙啊！多谢！

Which of the following, if true, most seriously weakens the plan’s chances for success?

1. The cost of raising soybeans has increased significantly over the past several years and is expected to continue to climb.
2. Tests of a newly developed, inexpensive pesticide have shown it to be both environmentally safe and effective against the insects that have infested cotton crops.
3. In the past several years, there has been no sharp increase in the demand for cotton and for goods made out of cotton.
4. Few consumers would be willing to pay significantly higher prices for cotton goods than they are now paying.
5. The species of insect that has infested cotton plants has never been known to attack soybean plants.

   Answer:

我不明白D为什么不对啊？谢谢！

谢谢大侠啊