In which case is the gravitational force between two objects the least? A. Two marbles are 10 centimeters apart.
B. Two bowling balls are 10 centimeters apart.
C. A marble and a golf ball are 10 centimeters apart.
D. A bowling ball and a marble are 10 centimeters apart.

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.