Six flats on a floor in two rows facing North and South are allotted to $P, Q, R, S, T$ and $U$.
$(i)$ $Q$ gets a North-facing flat and is not next to $S$.
(ii) $S$ and $U$ get diagonally opposite flats.
(iii) $R$,next to $U$,gets a South-facing flat and $T$ gets a North-facing flat.
Which of the other pairs,besides $SU$,are diagonally opposite to each other?

• A
  $QP$
• B
  $QR$
• C
  $PT$
• D
  $TS$