The locus of a point which moves so that it is always equidistant from the point A(a, 0) and B (- a, 0) is
A circle
Perpendicular bisector of the line segment AB
A line parallel to x-axis
None of these
Let point be (h, k) then, (h−a)2+k2=(h+a)2+k2
⇒ 4ha = 0 ⇒ h = 0. Hence x = 0.