Conclusion:- Newer Houses contain more indoor air pollution than older houses.

Reason:- Newer houses are built near the site of dumps or where automobile emissions are heavy.

To find:- A statement, if true, refutes the reason for that conclusion. This could be an alternative reason that is responsible for the disparity observed between older and newer homes.

(A) Indoor Pollution is taken care of by the air filtration system, but what about the outdoor pollution? Nothing has been mentioned about the outdoor pollution. Out of Scope.

(B) Easing of standards would impact older and newer homes alike, leaving scope for the aforementioned reason to be plausible. Not refuting the reason. Eliminated.

(C) This actually strengthens the reason mentioned. For newer houses in secluded rural areas are free of air pollution implies that newer houses in busy industrial areas where air pollution is imminent is so because of external factors. Eliminated.

(D) This statement also somewhat strengthens the mentioned reason for if warm weather conditions keep air trapped at the source, then houses near the source would be affected. Eliminated.

(E) This statement presents an alternate reason filling in on the disparity between older and newer homes and thus, is the answer.

IMO, Option E.