Explanation:

Let’s break down the clues step by step:

- There are unknown number of persons sitting in a line, all facing north.

- Three persons between P and Q, and Q is adjacent to R. Also, P is to the left of R.

- Z is 2nd to the right of R.

- Two persons between Z and Y, and Y is at one end. Y is not adjacent to R.

- R is 2nd to the right of A. A sits exactly in the middle.

- C is 6th from the left end.

- P is not to the right of C.

- Two persons between C and L.

- Two persons between P and M.

Let’s put these together:

- Start by placing A in the middle.

- Since R is 2nd to the right of A, so R is two places right of A.

- Z is 2nd to the right of R (so four right from A).

- Y is not at the end near Z since there are two people between Y and Z.

- C is 6th from the left and P isn’t to the right of C, so P is to the left or same as C.

- Three people between P and Q, and Q is adjacent to R, so only one way to place them.

- Continue placing others.

Finally, after following all clues:

- There are nine persons to the left of R.

Options:

- Three

- Nine

- Four

- Eleven

- None of these

Correct Answer: Option 2 (Nine)