Correct Answer - A
No light is emitted from the second polaroid, so `P_1` and `P_2` are perpendicular to each other
Let the initial intensity of light is `I_0`. So intensity of light after transmission from first polaroid`=I_0/2`.
Intensity of light emitted from `P_3, I_1=I_0/2cos^2theta`
Intensity of light transmitted from last polaroid, i.e., from `P_2=I_1cos^2(90^@-theta)=I_0/2 cos^2theta.sin^2theta`
`=I_0/8(2sinthetacostheta)^2=I_0/8sin^2 2theta`