Which of the following is not a metalloid? 

Aluminium 

The correct answer is option 3. Aluminium.

Among the options provided, the element that is not a metalloid is Aluminium.

Germanium and silicon are well-known metalloids. They exhibit properties intermediate between metals and non-metals. These elements are located along the diagonal band between metals and non-metals on the periodic table.

Tellurium is also a metalloid. It is located in the same group as selenium and is known for its semiconductor properties.

Aluminium, on the other hand, is a typical metal. It is a member of the Boron group (Group 13) in the periodic table and is classified as a metal due to its metallic properties such as conductivity, malleability, and ductility.