because Iron nail is wrapped with a copper wire so it's a solinoid and when the switch is off it gets magnetic field or the iron nail would behave like a magnet.
Step 1 gives you 3*(4x - 2) on the left hand side.
When you remove the brackets what you get is 3*4x - 3*2 12 x - 6 You have to distribute on both sides of the plus sign. The answer is the second one down.
