Six students, F, E, D, C, B and A, were studying around a square table in a college library, facing the centre. Four of them were sitting at the corners while two others were sitting at the exact centre of the sides. C and E were diagonally opposite to each other. A was not at any of the corner positions and was an immediate neighbour of both E and D. D was diagonally opposite to F. B was at the immediate right of F. No student sat between C and D as well as between E and F. Which student sat third to the left of B?
AD
BC
CA
DE