In the context of a model comparing comets and planets, the most relevant comparisons would be:
- Comets and planets revolve around the sun. (This is a fundamental similarity as both objects are part of the solar system and follow orbits due to gravitational forces.)
The other comparisons, such as size, composition, and orbital time periods, would generally not be accurate. For example, comets are typically much smaller than planets, they are composed of different materials (comets contain more ice and dust, while planets are made up of rock, metal, gas, etc.), and they often have much longer and more eccentric orbits, leading to differing orbital time periods. Hence, the first comparison about orbiting the sun is the most applicable.