Bank depositors in the United States are all financially protected against bank failure because the government insures all individuals' bank deposits.  An economist argues that this insurance is partly responsible for the high rate of bank failures, since it removes from depositors any financial incentive to find out whether the bank that holds their money is secure against failure.  If depositors were more selective, then banks would need to be secure in order to compete for depositors' money.

The economist's argument makes which of the following assumptions?

(A) Bank failures are caused when big borrowers default on loan repayments.

(B) A significant proportion of depositors maintain accounts at several different banks.

(C) The more a depositor has to deposit, the more careful he or she tends to be in selecting a bank.

(D) The difference in the interest rates paid to depositors by different banks is not a significant factor in bank failures.

(E) Potential depositors are able to determine which banks are secure against failure.

没有看懂题意  不明白为什么选E,请帮分析一下,谢谢!

没有看懂题意  不明白为什么选E,请帮分析一下,谢谢!

选一项,若选项取非，则论点不成立。

E取非，意为存款人不知道存钱到哪家银行比较安全，与since it removes from depositors any financial incentive to find out whether the bank that holds their money is secure against failure矛盾。

所以选E

题目的意思是：美国政府为所有存款人提供银行破产的存款赔偿是造成银行存在很高破产率的部分原因，因为这一措施使得存款人不再考虑他们将钱存入的银行是否会破产。如果存款人能够更具选择性，银行便需要在竞争中提高自身的安全。

E说潜在的存款人能够决定哪个银行更不容易破产，就是说他们能够selective更安全的银行，这样便能提高银行间的竞争，所以是argument的前提。