Two circular coils $P$ and $Q$ are fixed coaxially and carry currents $I_1$ and $I_2$ respectively.

• A
  If $I_2 = 0$ and $P$ moves towards $Q$,a current in the same direction as $I_1$ is induced in $Q$.
• B
  If $I_1 = 0$ and $Q$ moves towards $P$,a current in the opposite direction to that of $I_2$ is induced in $P$.
• C
  When $I_1 \neq 0$ and $I_2 \neq 0$ are in opposite directions,then the coils tend to move apart.
• D
  Both $(B)$ and $(C)$.