How many persons sit on a row ?

Given: A certain number of persons sit on a row and facing towards north direction. 

1) P sits at one of the extreme end.

2) Q sits three places away from P who sits six places away from R.

3) R and S sit immediate next to each other.

4) U sits fifth left of S who sits seven places away from T.

5) As many persons sit to the left of U as many persons to the right of Q. So, case 1 is eliminated.

6) Not more than 15 persons sit on a row. So, case 2(b) is eliminated. Hence, the final arrangement is as follows

After final arrangement we can conclude total 14 persons sit on a row.

Hence, the correct answer is 14.