Concept:After two persons interchange seats, each moves to the other's position, so the new neighbors of a person are the original neighbors of the other person.
Explanation:S and T interchange seats.
S moves to T's original seat.
Thus, S's new neighbours are exactly the persons who were originally neighbours of T.
From the given options, T's original neighbours must be U and Q.
Therefore, after the interchange, S's neighbours are U and Q.
Answer:U and Q