Detailed Solution:
The correct answer is “Aluminium”.
The answer is (4) Aluminium.
Iron, nickel, and cobalt are all classified as ferromagnetic metals. This means they have strong magnetic properties and are attracted to magnets.
Aluminium, on the other hand, is a diamagnetic metal. Diamagnetic materials have a weak repulsion to magnets. So, while a magnet won't necessarily pull on aluminium, it also won't be attracted to it.