The arrangement to store two magnets is shown by figures (a), (b), (c) and (d) in Fig. 13.2. Which one of them is the correct arrangement?

With time magnets lose their magnetic properties. So in order to retain their magnetic strength, the pair of magnets is kept with unlike poles in the same direction with a wooden block between them and metal plates made up of soft iron are placed across the poles as shown in figure (b). This arrangement preserves the magnetic strength of magnets by completing the magnetic circuit.