The correct answer is: B. At upper culmination.
A circumpolar star is a star that never sets or rises in the sky, as seen from a particular location on Earth. This is because the star’s circumpolar circle is above the horizon at all times from that location. The circumpolar circle is the circle of latitude around the Earth that marks the southernmost or northernmost latitude at which a circumpolar star can be seen.
The altitude of a star is its angle above the horizon. The altitude of a circumpolar star is maximum when it is at upper culmination, which is when the star is at its highest point in the sky. This occurs when the star is directly overhead at the observer’s location.
The altitude of a star is minimum when it is at lower culmination, which is when the star is at its lowest point in the sky. This occurs when the star is directly below the observer’s location.
East elongation and west elongation are the points in the sky where a star is directly east or west of the observer’s location. The altitude of a star is not maximum or minimum at these points.