[讨论]请教大全12-13，盼nn回复

13. Houses built during the last ten years have been found to contain indoor air pollution at levels that are, on average, much higher than the levels found in older houses. The reason air-pollution levels are higher in the newer houses is that many such houses are built near the sites of old waste dumps or where automobile emissions are heavy.
Which of the following, if true, calls into question the explanation above?
(A) Many new houses are built with air-filtration systems that remove from the house pollutants that are generated indoors.
(B) The easing of standards for smokestack emissions has led to an increase in air-pollution levels in homes.
(C) New houses built in secluded rural areas are relatively free of air pollutants.
(D) Warm-weather conditions tend to slow down the movement of air, thus keeping pollution trapped near its source. (E)
(E) Pressboard, an inexpensive new plywood substitute now often used in the construction of houses, emits the pollutant formaldehyde into the house.

我懂E是典型的他因。可是A 为什么不对？A说新房子有空气过滤系统，不就直接weaken“新房子空气质量比老房子差”的结论了嘛？还有C我也不明白，题目中解释是新房子建在垃圾区或者尾气严重的区域，那么C说新房子建在空气质量好的隐蔽处，不就直接weaken解释了嘛？