Answer:
oxygen is the answer......
B) small non-polar molecules. Small molecules can pass through the cell membrane through diffusion (does not require energy). The molecule being non-polar is an advantage because the tails of the phospholipid bilayer is hydrophobic (nonpolar), so it does not repel nonpolar molecules.

Unconventional or non criteria pollutants can include several toxic or non-toxic elements. Toxic chemicals, such as benzene, beryllium, PCBs, asbestos and vinyl chloride are man-made unconventional toxic pollutants that are regulated by the EPA. Other forms of unconventional pollution include noise, unpleasant odors and light pollution as well as aesthetic factors.
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