Explanation:

Let’s break this puzzle down step-by-step:

- Q is second from one end — that gives us an anchor.

- Only two people between Q and M. So: Q _ _ M.

- S is seventh to the right of M. So, count seven spots to the right—M _ _ _ _ _ _ S.

- L is exactly between Q and S. So, Q ... L ... S, with L equally spaced.

- O is third to the left of R. So, O _ _ R.

- Only one person between S and O.

- P is second to the left of N; N is fourth to the right of R (R _ _ _ N; P is before N).

- R is not next to S.

When you build the sequence, you get:

- Q _ _ M _ _ _ S 

- The distance between Q and S is nine (Q _ _ M _ _ _ S). M is third after Q, S is seven after M ? S is 10 spots after Q. So, Q _ _ M _ _ _ _ _ S (10 spots apart).

- L sits exactly in between Q and S, so with 10 seats between, L is placed after 5: Q _ _ M _ L _ _ _ S.

- Placing O and R: Since S and O have one seat in between, and O is third left of R, you fit them after S.

- Fill in rest: Placing N and P per the clues, everything falls into a sequence of 21 seats.

So the correct answer is:

Option:2, 21

Other options don’t work because the spacing and positions fall apart if you try more or fewer seats. 21 is the only number that fits every detail.