GMAT问题，高人求解~

zelda爱star

1.Companies considering new cost-cutting manufacturing processes often compare the project results of making the investment against the alternatve of not making the investment with costs, selling prices, and share of market remaining constant.

Which of the following, assuming that each is a realistic possibility, constistutes the most serious disadvantage for companies of using the method above for evaluating the financial benefit of new manufacturing process?

D Competitors that do invest in a new process might reduce their selling prices and thus take market share away from companies that do not.

E The period of year chosen for averaging out the cost of the investment might be somewhat longer or sorter,thus affecting the result.
关于D，公司不是在对比要不要invest么？那么为什么要讨论invest的话，会有reduce prices呢？

2.Aachaeologists seeking the location os a ledendary siege and sestruction of a city are exavating in aeveral possible places, including a middle and a lower layer of a large mound. The bottom of the middle layer contains some pieces of pottery of type 3 ,known to be from a later period that the time of the destruction of the city, but the lower layer doed not.
想问一下，这段话要表示什么意思呢？这个地方到底是不是location呢？是说虽然middle layer不是，但是lower layer证明是？