As polaroid examines two adjacent plane polarised beam A and B whose planes of polarisation are mutually perpendicular. In the first position of the analyser, beam B shows zero intensity. From this position a rotation `30^(@)` shows that thebeams have same intensity. The ratio of intensity of the two beam `I_(Z) & I_(B)`
A. `1:3`
B. `3:1`
C. `sqrt(3):1`
D. `1: sqrt(3)`