Which of the following is the chief ore of aluminium?

Bauxite

The correct answer is option 3. Bauxite.

The chief ore of aluminum is: Bauxite.

Bauxite is the primary source of aluminum and is composed mainly of aluminum oxide minerals such as gibbsite, boehmite, and diaspore, along with other impurities. It typically forms in tropical or subtropical regions through the weathering of aluminum-rich rocks under humid conditions. Bauxite deposits are found in various locations around the world, with significant reserves in countries such as Australia, Guinea, Brazil, China, and India. The aluminum extracted from bauxite is used in a wide range of applications, including transportation (such as automobiles and aircraft), packaging, construction, and electrical transmission lines.