How many objects must be present in a system to demonstrate gravity as a force of attraction?

The organ that has two atria and one ventricle is the

People keep spending additional units of a particular resource on a want until their marginal benefit is  decreasing withgreater thanless thannot affected by  their marginal cost.

What did the pattern of earthquakes in the wadati-benioff seafloor zones show scientists? a.) earthquakes occur where the ocean floor reaches its highest temperatures. b.) many earthquakes take place 700 kilometers below the seafloor. c.) slabs of ocean floor return to the mantle in subduction zones. d.) ocean - trenches cause earthquakes.