For the lines to be perpendicular the angle between them must be 90 degree.
So for the line r perpendicular to line r means that angle between these two line is of 90 degrees.
The angle between line r and line p are,
So all these are of 90 degrees as these are angle between two perpendicular line.
So
Since angle 3 and angle 6 are equal to 90 degrees.
So opton B, C, and E are correct.