To avoid double refraction of light propagating inside a uni

To avoid double refraction of light propagating inside a uniaxial crystal (in which O- and E-waves travel along the same direction with the same velocity), the angle theta between the light ray and optical axis of the crystal must be theta = 0 degree (Parallel), theta = 90 degree (Perpendicular), theta = plusminus 45 degree, theta = 0 degree or theta = 90 degree depending on uniaxial positive or negative crystal.

Solution

option A is correect one to avoid double refraction in uni axial crystal