What characteristic is common among the inner planets?

• A. They are gaseous
• B. They have rings
• C. They are rocky
• D. They are large in size

Answer: (C)

The inner planets, which include Mercury, Venus, Earth, and Mars, are characterized by their rocky surfaces, making option C the correct choice. These planets are primarily composed of rock and metal, giving them a solid structure as opposed to the outer planets, which are mainly gas giants.

The composition of the inner planets leads to features such as mountains, craters, and valleys, which are typical of a rocky environment. Their smaller size compared to the outer planets, along with their proximity to the sun, results in higher temperatures that contribute to their geological makeup.

In contrast, options that describe the inner planets as gaseous or large in size are inaccurate because the inner planets do not have significant atmospheres like the gas giants and are generally smaller. The presence of rings is also a characteristic of some outer planets, which is not applicable to the inner planets. Thus, the defining characteristic of being rocky distinctly describes the inner planets.