12. Bacteria can be classified into which of the following groups by the carbon source: 1. Autotrophs 2.Prototrophs 3. Heterotrophs 4.Auxotrophs

The correct answer is 1. Autotrophs.<br /><br />Autotrophs are bacteria that can produce their own organic compounds from inorganic substances, such as carbon dioxide, using energy from sunlight or chemical reactions. They are able to synthesize their own carbon source and do not rely on external organic compounds for carbon.