Three glass prisms A, B and C of same refractive index are placed in contact with each other as shown in figure, with no air gap between the prisms. Monochromatic ray of light OP passes through the prism assembly and emerges as QR. The conditions of minimum deviation is satisfied in the prisms

• A

  A and C 

• B

  B and C

• C

  A and B 

• D

  In all prisms A, B and C