The inner planets—mercury, venus, earth, and mars—are believed to have been formed by answers

These planets are formed by rocks.

Explanation:

There are 2 types of planets in Our Solar System:

1. Inner planets: There are 4 planets which are considered as inner planets, these are Mercury, Venus, Earth and Mars. These planets are small and have rocky surface. Their time of revolution around the Sun is less than the outer ones. These planets have maximum number of moon till 2.

2. Outer planets: There are 4 planets which are considered as outer planets, these are Jupiter, Saturn, Uranus and Neptune. These planets are large and gaseous planets. Their time of revolution around the Sun is more than the inner ones. These planets have many moon.

Hence, the inner planets are believed to be formed of rocks.

b would be the answer

at positions a, g kinetic energy is maximum.

at position d, potential energy is maximum.