Fridge magnets

This task is about the results of two investigations about magnets.

Question

a)  Grandma was given a magnetic cat for her birthday. She stuck the cat magnet on the fridge door. What was the fridge door made of? (Choose one.)

    • Aluminium

    • Steel

    • Plastic

    • Copper

Question

b)  Four different magnets were used to pick up metal paper clips
 
 

Which magnet was the strongest?

 
 

    • A

    • B

    • C

    • D

How do you know this magnet was the strongest?