Explanation:

- Let's break down the information given:

- Six people sit between L and J.

- The number of people between M and P is the same as between M and L.

- Two people sit between P and R.

- Three people sit between M and N.

- K is third to the right of N.

- K is second to the left of P.

- Only three people are to the left of L.

- R is at one end of the row.

- The focal points are: L, J, M, P, R, K, and N.

- From L, move three places to the right to set a boundary on the left side: This means L is the fourth person.

- R has to be at one end, so let's place R first on this basis.

- Set up considering placements and logical deductions:

- It's determined that there are 8 persons between M and P.

- Therefore, the answer is confirmed: Option:4, 8 is correct.