Which statement describes the density of the inner planets? All the inner planets are dense.
The inner planets are less dense than the outer planets.
Earth is dense, while the other inner planets are not.
Mercury and Venus are dense, while Earth and Mars are not.

All inner planets are dense

Explanation: Mercurius, Venus, Earth and are more dense than Jupiter  

and Saturnus

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.