The diagrams present three different metal rods P, Q and R, positioned inside coils of wire. Small iron nails are arranged on a wooden bench beneath the rods. Diagram 1 illustrates the arrangement when electric currents flow in the wires. Diagram 2 illustrates the arrangement after the currents have been switched off. Which row correctly identifies the metal rods?
- AP: copper, Q: soft iron, R: steel
- BP: soft iron, Q: copper, R: steel
- CP: steel, Q: soft iron, R: copper
- DP: copper, Q: steel, R: soft iron