Concept:Planets are classified based on composition and location; the four innermost planets are rocky and solid.
Explanation:The four planets closest to the Sun are Mercury, Venus, Earth, and Mars.
These planets have solid, rocky surfaces, similar to Earth's structure.
They are known as terrestrial planets, meaning "Earth-like".
In contrast, the outer planets like Jupiter, Saturn, Uranus, and Neptune are gas giants or Jovian planets, much larger and composed mainly of hydrogen and helium.
Terrestrial planets are smaller, denser, and have fewer moons.
Therefore, the correct classification for the innermost four planets is terrestrial planets.
Answer:A. Terrestrial planets