Which is most likely a source of air pollution? littering, CFCs, oil spill , runoff

the best answer is, earth strong )

explanation:

b. lithosphere, asthenosphere, mesosphere   is the answer most likely

the answer to your question is tooth decay.

the solute can move "downhill," from regions of higher to lower concentration, relying on the specificity of the protein carrier to pass through the membrane. this process is called passive transport or facilitated diffusion, and does not require energy.