Using the map, we are asked to name the stars. They can be interpreted as points and thus we can name them by letters.
This is just one of million possible ways to name them.
A line segment is only the part of a line between two points. The stars in the figure are interpreted as points and let's use the name we stated in part A.
For example, two line segments are ST and TA.
Since is a two-dimensional map all stars are on the same plane. Therefore, we can use any three points. For example NRW.