A. Many new houses are built with air-filtration systems that remove from the
house pollutants that are generated indoors.
This one is irrelevant.
B.The easing of standards for smokestack emissions has led to an increase in
air-pollution levels in homes
This might be true for both new and old houses.
C.New houses built in secluded rural areas are relatively free of air pollutants
This one strengthens.
(D) Warm-weather conditions tend to slow down the movement of air, thus
keeping pollution trapped near its source.
This is true for both new and old houses
(E) Pressboard, an inexpensive new plywood substitute now often used in the
construction of houses, emits the pollutant formaldehyde
into the house
This is right because it gives a alternate reason for the cause.
Thanks
raama