The correct answer is: A. At culmination.
Polaris is the North Star, and it is always located directly above the North Pole. This means that it can be used to determine the azimuth, which is the direction of a line from a point to another point, relative to the north-south line.
Polaris is most easily observed for the determination of the azimuth when it is at culmination, which is when it is at its highest point in the sky. This occurs twice a day, once at noon and once at midnight.
When Polaris is at culmination, it is directly overhead, and its azimuth is 0 degrees. This means that it can be used as a reference point to determine the azimuth of other objects in the sky.
The other options are incorrect because they do not describe when Polaris is best observed for the determination of the azimuth.
- Option B, “At elongation,” is incorrect because elongation is the maximum angular distance between a planet and the Sun. This means that Polaris is not at elongation when it is directly overhead.
- Option C, “Neither at culmination nor at elongation,” is incorrect because Polaris is best observed for the determination of the azimuth when it is at culmination.
- Option D, “Either at culmination or at elongation,” is incorrect because Polaris is not best observed for the determination of the azimuth when it is not at culmination.