Final answer:
The characteristic that is not true for inner planets is "They have substantial atmospheres" as not all terrestrial planets have significant atmospheres, with Mercury having a thin one, whereas gas giants are known for their substantial gaseous envelopes.
Step-by-step explanation:
Characteristics of Inner Planets
The question regarding the characteristics of the inner planets includes multiple options, but the one that is not a characteristic of inner planets is E) They have substantial atmospheres. The inner or terrestrial planets—Mercury, Venus, Earth, and Mars—are smaller and have solid, rocky surfaces with higher densities. Their orbits are closer to each other than those of the outer planets. However, not all inner planets have substantial atmospheres; for instance, Mercury has a very thin atmosphere compared to Earth.
The outer planets, also known as the giant or jovian planets, typically have deep atmospheres composed of gases such as hydrogen and helium. Earth is unique among the terrestrial planets for having a dense and life-supporting atmosphere. Therefore, the presence of a substantial atmosphere is more characteristic of the gas giants rather than the rocky planets of the inner solar system.