一道没解决的题

Proposals for extending the United States school year to bring it more in line with its European and Japanese counterparts are often met with the objection that curtailing the school’s three-month summer vacation would violate an established United States tradition dating from the nineteenth century. However, this objection misses its mark. True, in the nineteenth century, the majority of schools closed for three months every summer, but only because they were in rural areas where successful harvests depended on children labor. If any policy could be justified by those appears to tradition, it would be the policy of determining the length of the school year according to the needs of the economy.

25.   Which one of the following principles, if accepted, would provide the strongest justification for the conclusion?

(A) That a given social policy has traditionally been in force justifies maintaining that policy only if doing so does not conflict with more pressing social needs.

(B) Appeals to its own traditions cannot excuse a country from the obligation to bring its practices in line with the legitimate expectations of the rest of the world.

(C) Because appeals to tradition often serve to mask the real interests at issue, such appeals should be disregarded.

(D) Traditional principles should be discarded when they no longer serve the needs of the economy.（E）

(E) The actual tradition embodied in a given practice can be accurately identified only by reference to the reasons that originally prompted that practice.

为啥不是D呢，选E

谢谢lurkNN

能翻译下E么，觉得不是很懂它的意思