The Synodic Period of a Superior Planet in Motion Around

The synodic period of a superior planet in motion around the Sun, as viewed from Earth, is defined as the time between:

A) two successive appearances of the planet at its highest point in the observer's sky.
B) two successive passages of Earth through the vernal equinox.
C) conjunction and opposition on any orbit.
D) two successive passages through identical configurations, for example, two opposition positions.