Which of the following is a property of gas giants?

Gas giants, such as Jupiter and Saturn, are characterized by their thick atmospheres composed primarily of hydrogen and helium. These massive planets do not have a defined solid surface; instead, they possess layers of gas that become denser as you move deeper into the atmosphere. The thick atmospheres contribute to their large sizes and distinctive weather patterns, including storms and high-speed winds. This atmospheric composition is fundamental to the classification of these planets as "gas giants."

In contrast, the other characteristics listed, such as being solid at room temperature, having a brittle structure, or high density, do not apply to gas giants. Being solid is typical of terrestrial planets, while a brittle structure is more associated with rocky materials. Gas giants, due to their gaseous nature, have lower densities compared to rocky planets, and their structure is not characterized as brittle.