Which feature is NOT characteristic of gas giants?

Gas giants, such as Jupiter and Saturn, are primarily characterized by their thick atmospheres composed of hydrogen and helium, which creates a significant layer of gaseous clouds surrounding them. These planets are indeed large in size, often many times the volume of Earth, allowing them to hold onto vast amounts of gas without a solid surface beneath.

The correct answer identifies the solid surface as a feature that is not characteristic of gas giants. Unlike terrestrial planets like Earth or Mars, which have solid, rocky surfaces, gas giants do not have a well-defined solid surface. Instead, their atmosphere gradually transitions into their denser, gaseous interiors. While gas giants can have solid cores, the majority of their mass is in gaseous form, leaving them without a solid ground that we typically think of when referring to a "surface."

Gas giants can also be surrounded by rings, as evidenced by Saturn’s extensive ring system. Thus, the presence of a solid surface is distinctly not a trait of gas giants, aligning with the features that define them uniquely within the solar system.