they are often said to be more productive if more letters are delivered per postal worker. But is this really true?

what if more letters are lost or delayed per worker at the same time that more are delivered?

The objection implied above to the productivity measure described is based on doubts about the truth of

which of the following statements?

(A) Postal workers are representative of service workers in general.

(B) The delivery of letters is the primary activity of the postal service.

(C) Productivity should be ascribed to categories of workers, not to individuals.

(D) The quality of services rendered can appropriately be ignored in computing productivity.

(E) The number of letters delivered is relevant to measuring the productivity of postal workers.

OG对D的解释很模糊，大家能否说说自己的看法。我觉得E是答案。因为信的数量和衡量服务质量有关，提出有关就说明不是唯一指标，这不也是反对的一个基础吗？

原文:more letters are delivered per postal worker ->be more productive, 也就是说delivered信的数量是充分条件.

从what if more letters are lost or delayed per worker at the same time that more are delivered可看出反对者关注的是丢失的信,反对者并没有number of letters delivered与生产率的关系. 我觉得这是排除E的重点.