If two identical bar magnets, each of length l, pole strength m, and magnetic moment M are placed perpendicular to each other with their unlike poles in contact, the magnetic moment of the combination is :

Question

$$\begin {array} {1 1} (a)\;\frac{M}{\sqrt 2} & \quad (b)\;lm(\sqrt 2) \\ (c)\;2 lm (\sqrt 2) & \quad (d)\;2M \end {array}$$