Which characteristic best describes what the outer planets share with each other?
A. They are all very warm, similar to Venus.
B. They are made mostly of gaseous materials
C. They orbit the sun opposite to Earth
D. They have no moons that orbit them
B. They are made mostly of gaseous materials
B. They are made mostly of gaseous materials
The correct answer is B. They are made mostly of gaseous materials.
To arrive at this answer, you can eliminate options A, C, and D because they are not characteristics shared by all outer planets.
Option A states that the outer planets are all very warm, similar to Venus. However, this is not true for all outer planets. For example, Uranus and Neptune have extremely cold temperatures.
Option C suggests that the outer planets orbit the Sun opposite to Earth. This statement is incorrect because only two outer planets, Uranus and Venus, have retrograde orbits (opposite to the direction of Earth's orbit around the Sun). The other two outer planets, Jupiter and Saturn, have prograde orbits (same direction as Earth's orbit).
Option D states that the outer planets have no moons orbiting them. This is also false because all four outer planets have moons.
By process of elimination, the correct statement is option B: the outer planets are made mostly of gaseous materials. All the outer planets, Jupiter, Saturn, Uranus, and Neptune, have thick atmospheres predominantly composed of gases, such as hydrogen and helium.