Which option accurately describes an unbalanced force?

a) each cement block supports a2-n force, but when the foundation is built in a staggered pattern it can support 2,000 n

b) three rows of cement blocks form a foundation for a house, and the house rests on this foundation

c) a 2-n force presses down on the cement block at the same time as a 1.5-n force presses up on the cement block

d) the force of a house pressing down on its foundation of cement blocks is 3,000 n.