请教狒狒逻辑讲义上的一道题-->bigmouse转移

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例1. Because incumbent members of Congress are given a great deal of attention by the news  media and because they enjoy such perquisites as free mail privileges and generous travel allowances, incumbents enjoy an overwhelming advantage over their challengers in elections for the United States Congress.

  Which of the following, if true, best supports the claim above?

(A) In the last congressional elections, incumbents met with a larger number of lobbyists than did challengers.

(B) In the last congressional elections, 98 percent of the incumbents in the House of Representatives who were seeking reelection won.

(C) Incumbent members of Congress are frequently critical of the amount of attention given to them by the news media.

(D) The support that political station action committees provide to challengers for congressional seats often compensates for the perquisites enjoyed by incumbent members of Congress.

(E) Of all incumbent senators surveyed before the last congressional elections, 78 percent said that their challengers did not pose a serious threat to their chances for reelection.

请问答案是什么？讲义中说此题为演绎题中的加强，讲义中说此类题有两种解题方法：桥梁和B存在。我刚接触GMAT逻辑，请问这两种方法怎么用，此题又该如何借呢？请NN指点，感激不尽！