Two beams, A and B of plane polarised light with mutually perpendicular planes of polarisation are seen through a polaroid. From the position, when the beam A has maximum intensity (and beam B has zero intensity), a rotation of polaroid through 30° makes the two beams appear equally bright. If the initial intensities of the two beams are IAand IB respectively, then IA/IB equals
(a) 3
(b) 3/2
(c) 1
(d) 1/3
