The diagrams illustrate three different metal rods P, Q and R placed inside wire coils. Small iron nails are set on a wooden bench below the rods. Diagram 1 shows the arrangement when electric currents flow in the wires. Diagram 2 shows the arrangement when the currents are turned off. Which row correctly names 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