The plane of polarisation ofa plane polarized light rotates by 60° after passing through a wave plate. the pass-axis of the wave plate is at an angle a with res

The answer is B and C both. Please explain this. The plane of polarisation ofa plane polarized light rotates by 60° after passing through a wave plate. The pass-axis of the wave plate is at an angle a with respect to the plane of polarisation of the incident light. The wave plate and a are (A)A/4. 60 B) 1/2. 30 C) 1/2, 120° (D) 1/4, 30