Air particles flow from areas of __.(Mark the one best answer.) A high pressure to low pressure, until the pressures are equal.

B. low pressure to high pressure, until the pressures are equal.

C. medium pressure to high pressure, until the pressures are equal.

D. low pressure to medium pressure, until the pressures are equal.

15. which of the following is not human-caused groundwater pollution? a. water in an aquifer dissolves elements such as arsenic and mercury from surrounding rock. b. water in an aquifer is contaminated by leachate that seeps into the ground from a landfill. c. water in an aquifer becomes polluted with chemicals used in hydraulic fracturing, or fracking. d. water in an aquifer absorbs harmful bacteria from the drainage field of a septic tank.