Which one of the following bodies would NOT exhibit retrograde motion if observed from Mercury?

Question

Quizplus · Accepted Answer

Retrograde motion is the apparent backward motion of a planet as seen from another planet with a shorter orbital period. Since Mercury has the shortest orbital period in the solar system, it would not observe the Sun exhibiting retrograde motion. The other planets, Venus, Earth, and Mars, have longer orbital periods than Mercury and therefore could exhibit retrograde motion as seen from Mercury.

Which One of the Following Bodies Would NOT Exhibit Retrograde