Step-by-step seating arrangement:

• Total positions = 11 (numbered 1 to 11 from left to right).
• From (C): Q is at an end and M is second to the right of Q $\implies$ Q is at Position 1, M is at Position 3.
• From (B): V is neighbour to M and N $\implies$ V is at Position 4, N is at Position 5 (since Position 2 cannot place V between M and N). Also, V (Pos 4) is third to the left of S $\implies$ S is at Position 7.
• From (A) and (D): P is second to the right of O, T is immediate left of P, R is immediate right of P $\implies$ block is O _ T P R. T is third to the right of U $\implies$ U must be at Position 6, making T at Position 9, O at Position 8, P at Position 10, R at Position 11.
• The only remaining position, Position 2, is filled by W.
  Full arrangement: Q(1) - W(2) - M(3) - V(4) - N(5) - U(6) - S(7) - O(8) - T(9) - P(10) - R(11).
  (F) The center person of 11 friends is at Position 6, which is U.

Direct derivation from seating order:

• Complete arrangement: Q - W - M - V - N - U - S - O - T - P - R.
• S is sitting at Position 7.
• The people sitting to the right of S (positions 8, 9, 10, and 11) are O, T, P, and R (OTPR).

Option verification against seating arrangement:

• Between S(Pos 7) and P(Pos 10) are O and T (2 persons, not 3 - False).
• W is at Pos 2 (between Q and M, not M and V - False).
• V is at Pos 4, N is at Pos 5, and U is at Pos 6 $\implies$ N is strictly between V and U (True).
• S and O are to the left of T (False).

Position interchange deduction:

• The two extreme ends originally are Position 1 (occupied by Q) and Position 11 (occupied by R).
• Q interchanges with P $\implies$ Position 1 is now occupied by P.
• W interchanges with R $\implies$ Position 11 (the other end) is now occupied by W.
• Therefore, the friends occupying both ends of the row are P and W.