P and Q are fixed points and X is a variable point which moves so that angle PXQ = 45o. What is the locus of x?

A.
A pair of straight lines parallel to PQ 
B.
The perpendicular bisector of PQ 
C.
An arc of a circle passing through P and Q 
D.
A circle with diameter PQ 
E.
The bisector of angle PXQ