From the figure in the question,
Since PR = RQ, Then
The line RS divides the line segment PQ into two equal halves
Hence
Also, the angle at R is 90 degree
Therefore line RS is perpendicular to line PQ
Hence
Also,
since PR = RQ
Then, R is the mid-point of PQ
Hence
Therefore
The following are the corrcet answers
1. Line RS is a segment bisector
2. Line RS is a perpendicular bisector
3. R is the midpoint of a segment in the diagram