Seven friends, M, N, O, P, Q, R and S, are sitting in a straight line, all facing towards the north. N is sitting at the middle position. M is sitting between Q and P. Q is sitting to the immediate left of N. S is sitting to the immediate left of O. M and O are not sitting at any of the ends. Who is sitting at the right end?

A

R

B

Q

C

N

D

P