lsat sec10 4-1

1. People who accuse the postal service of incompetence and inefficiency while complaining of the proposed five-cent increase in postal rates do not know a bargain when they see one. Few experiences are more enjoyable than reading a personal letter from a friend. Viewed in this way, postal service is so underpriced that a five-cent increase is unworthy of serious debate.
The reasoning in the argument is flawed because the argument
(A) suggests that the postal service is both competent and efficient, but does not establish how competence and efficiency should be measured
(B) claims that the proposed increase is insignificant but does not say at what level the increase would be worthy of serious debate
(C) confuses the value of the object delivered with the value of delivering that object
(D) appeals to an outside authority for support of a premise that should be established by argument
(E) fails to establish whether or not the critics of the postal service are employees of the postal service

为什么答案是c呢？ 答案看不懂啊。

把传送物品这个动作的价值和被传送物品本身的价值混淆了