9.     Technically a given category of insurance policy is underpriced if, over time, claims against it plus expenses associated with it exceed total income from premiums. But premium income can be invested and will then yield returns of its own. Therefore, an underpriced policy does not represent a net loss in every case.

The argument above is based on which of the following assumptions?

(A) No insurance policies are deliberately underpriced in order to attract customers to the insurance company offering such policies.

(B) A policy that represents a net loss to the insurance company is not an underpriced policy in every case.

(C) There are policies for which the level of claims per year can be predicted with great accuracy before premiums are set.

(D) The income earned by investing premium income is the most important determinant of an insurance company’s profits.（E）

(E) The claims against at least some underpriced policies do not require paying out all of the premium income from those policies as soon as it is earned.

请NNN们来指点一下此题如何分析.

E is correct. 取非: if premium needs to be paid back immediately, then there is no time for it to yield income, then the conclusion won't hold.

E is the only one that links premium, income and claim.