Which planets are classified as terrestrial planets?

The classification of planets into terrestrial and gas giants is based on their physical characteristics and composition. Terrestrial planets, which include Mercury, Venus, Earth, and Mars, are defined as rocky bodies with solid surfaces. They are typically smaller and denser than their gas giant counterparts, and they have relatively thin atmospheres compared to the massive gaseous envelopes surrounding the gas giants.

These terrestrial planets share several key features: they all have a solid crust, are composed primarily of silicate rocks and metals, and have relatively high surface temperatures due to their proximity to the Sun (in the case of Mercury, Venus, and Earth) or their size and geological activity (like Mars).

In contrast, the other provided options contain either gas giants or do not represent the correct group of terrestrial planets. Jupiter, Saturn, Uranus, and Neptune, for instance, are classified as gas giants or ice giants due to their massive sizes and primarily gaseous compositions. This distinction is crucial for understanding the solar system's structure and the different conditions that exist on each type of planet.