Ddt, dde, pcbs and pbdes are all
ddt, dde, pcbs and pbdes are all
a
biodegradable and do not persist in the environment
b
toxic at the organism level but not at the ecosystem level
c
teratogens
non-biodegradable and subject to bioaccumulation and/or bioamplification
d
approved for use as pesticides by the epa

The answer is C teratogens non-biodegradable and subject to bioaccumulation and/or bioamplification 

DDT () is persistent, non-degradable insecticide and organic pollutant readily accumulated to soils and consequently affects organisms.
DDE () is non-degradable pesticide toxic to birds at the first place.
PCBs (polychlorinated biphenyls) are non-degradable organic compounds  very toxic to the environment.
PBDEs (polybrominated diphenyl ethers) are non-degradable compounds very toxic to the environment, even able to affect brains of animals in the development period.

significant amounts of nitrogen oxides, carbon monoxide, and other pollution

explanation:

passenger vehicles are a major pollution contributor, producing significant amounts of nitrogen oxides, carbon monoxide, and other pollution. in 2013, transportation contributed more than half of the carbon monoxide and nitrogen oxides, and almost a quarter of the hydrocarbons emitted into our air.

the correct answer would be 6 feet.