Construct a perpendicular bisector from a point to a line

Maths

a) A straight line which is parallel to another line

b) A straight line which intersects another straight line at any point

c) A straight line which intersects another straight line through the midpoint

a) Set the compass to more than half of the length of the line

b) Set the compass to less than half of the length of the line

c) Set the compass to a quarter of the length of the line

Which of these is the correct first step to create a perpendicular bisector?