The locus of the centre of the circle which cuts a chord of length 2a from the positive x–axis and passes through a point on positive y–axis distant b from the origin is
(a) x2 + 2by = b2 + a2
(b) x – 2by = b2 + a2
(c) x + 2by = a2 – b2
(d) x2 – 2by = b2 – a2
