Correct option is D
Given - A, B, C, D, R, S and T are sitting around a circular table facing the centre of the table. Only four people sit between B and D when counted from the right of B. B sits third to the left of C. T sits third to the left of R. S is an immediate neighbour of both D and C

Two people (R, C) sit between A and S when counted from the right of A.
Option D is correct.