In an incandescent electric bulb, the filament is the part of the bulb that emits light when it is heated. The filament is made up of tungsten, which is option 3. Tungsten is chosen as the material for the filament because it has a very high melting point and is able to withstand the high temperatures generated when the bulb is turned on.

Option 1, aluminium, is not the correct answer. While aluminium is a metal commonly used in various applications, it cannot be used as the filament in an incandescent bulb because it has a relatively low melting point and would quickly deform or melt when exposed to the high temperatures generated by the bulb.

Option 2, copper, is also not the correct answer. While copper is used in electrical wiring due to its excellent electrical conductivity, it is not suitable for use as a filament because it has a lower melting point than tungsten.

Option 4, silver, is also not the correct answer. Silver is a highly conductive metal and is often used in electrical contacts, but it has a lower melting point than tungsten and would not be able to withstand the high temperatures required for the filament in an incandescent bulb.