question: The Placement and direction of Proximal grooves on 3/4th crown on molar teeth:
opa: Placed in buccal half and with buccal lingual divergence.
opb: Placed in buccal half with lingual to buccal divergence.
opc: Placed in the centre of the crown with buccal to lingual divergence.
opd: Placed in the lingual half with lingual to buccal divergence.