Seven friends M, N, O, P, Q, R and S, each has a different height. Only two people are taller than Q. P is taller than Q but shorter than O. M is taller than R but shorter than S.
Only three people are taller than S. N is the shortest among all. The height of how many persons is between the heights of Q and R?

A

2

B

4

C

1

D

3