Five persons P, Q, R, S and T are to be seated in a row, all facing the same direction, but not necessarily in the same order. P and T cannot be seated at either end of the row. P should not be seated adjacent to S. R is to be seated at the second position from the left end of the row. The number of distinct seating arrangements possible is:

The correct answer is 3.

Let us analyze the problem step-by-step to find all possible seating arrangements for the five persons P, Q, R, S, and T in a row of five seats (numbered 1 to 5 from left to right):

Step 1: Position R in the row
According to the given constraints, R must be seated at the second position from the left end of the row (position 2).
Seating layout: _ , R, _ , _ , _

Step 2: Identify positions for P and T
We are given that P and T cannot be seated at either end of the row (positions 1 and 5).
Since position 2 is already occupied by R, the only remaining non-end positions for P and T are positions 3 and 4.
Therefore, P and T must occupy positions 3 and 4. This gives us two cases to consider:

Case 1: P is at position 3 and T is at position 4
The layout is: _ , R, P, T, _
The remaining two persons, Q and S, must occupy the ends (positions 1 and 5).
Since P is at position 3, its adjacent neighbors are R (at position 2) and T (at position 4). Placing S at either position 1 or position 5 will not make S adjacent to P.
Thus, both arrangements are valid:
1. Q, R, P, T, S
2. S, R, P, T, Q

Case 2: T is at position 3 and P is at position 4
The layout is: _ , R, T, P, _
Again, Q and S must occupy positions 1 and 5.
Here, P is at position 4, so its adjacent positions are 3 (occupied by T) and 5. To ensure P and S are not adjacent, S cannot be placed at position 5.
Therefore, S must be placed at position 1, and Q must be placed at position 5. This gives us only one valid arrangement:
3. S, R, T, P, Q
(Note: The arrangement Q, R, T, P, S is invalid because P and S would be adjacent at positions 4 and 5).

Conclusion:
Summing up the valid arrangements from both cases, we get exactly 3 distinct seating arrangements:
1. Q, R, P, T, S
2. S, R, P, T, Q
3. S, R, T, P, Q