Conclusion: The price of product A will rise considerably.
Premise: Supply of Material X, which is essential for the manufacture of product A, is cut by flooding, thus decreasing the production and supply of product A.
Assumption:
Manufacturing is the only source of the supply. [therefore, if manufacturing decreases, supply decreases, leading to higher prices.]
We need to weaken the argument.
A. Alternative measures have been found that help alleviate some of the damage caused by the floods.
Irrelevant to the argument. Incorrect
B. Last year the demand for product A was lower than had been anticipated.
We want to know about the future. Incorrect
C. The price of product A has remained stable during the past year.
Again, we want to know about the future. Incorrect
D. Substantial inventories of material X have been stockpiled during the past year.
Here, this new info attacks the assumption that manufacturing is the only source. If there are enough inventory that can make up for the loss in production, prices will not decrease.
CorrectE. Over the past year, scientists have been researching many new alternatives that may eventually be able to replace product A.
Irrelevant to the argument. Incorrect