Question

which phrase describes the composition of the outer planets?
are gaseous
contain water
have high densities
are made mostly of liquid

Explanation:

The outer planets (Jupiter, Saturn, Uranus, Neptune) are also known as gas giants. They are mainly composed of hydrogen and helium in gaseous form. While they may have some water - related compounds in their atmospheres or interiors (but this is not the main composition description), their high - density statement is incorrect as they have lower densities compared to inner rocky planets. And they are not made mostly of liquid (though they may have liquid layers, the dominant state in their large volumes is gaseous).

Answer:

are gaseous