What are the common characteristics of gas giant planets?

Gas giant planets, such as Jupiter and Saturn, are characterized by their massive sizes and thick atmospheres primarily composed of hydrogen and helium. These gases dominate their compositions, creating deep layers of gas surrounding any potential solid cores. Unlike terrestrial planets, which have solid surfaces and are made largely of metal and rock, gas giants lack a well-defined solid surface, further distinguishing them.

The significant presence of hydrogen and helium in their atmospheres contributes to their extensive and dynamic weather systems, such as storms and high-speed winds. The thick atmospheres of gas giants can encompass various cloud layers and contribute to their vibrant appearances.

This option best reflects the fundamental nature of gas giants, contrasting with other choices that suggest solid surfaces or compositions dominated by materials like iron and silica, which are not typical for these massive planets.