Which of the following best describes solids?
a. solids are low in density and compressible.
b. solids are high in density and compressible.
c. solids are low in density and incompressible.
d. solids are high in density and incompressible.

In my opinion I would pick D. 

Multiple answers could be chosen, just due to the fact that a solid is nothing more than just an object that cannot change it's physical shape into an object; just as water would. a solid can have a low density; such as paper, plastics, or even just a piece of wood. 

But think of a block of ice. You can break it, and crush it. It cannot be formed into any other shape. If you did break it, it only would make more ice fragments. And it's next phase is a liquid; if it were to be melted.