Hint: Most extensive metabolic diversity is exhibited by organisms that are primitive. These organisms differ from eukaryotes in various aspects; i.e. they do not have a well-defined nucleus, cell organelles, etc.
Complete answer: Kingdom Monera includes bacteria that are unicellular organisms with naked circular DNA which is not enclosed by the nuclear envelope, and organelles such as mitochondria, plastids, Golgi apparatus, lysosomes, ER are absent. Bacteria have the most extensive metabolic diversity and are both autotrophs or heterotrophs. Autotrophs are either photosynthetic or chemosynthetic. They synthesize food from inorganic substances such as carbon dioxide and heterotrophic bacteria by utilizing organic compounds to produce energy.
a) Kingdom Plantae include plants that are autotrophic and prepare food by photosynthesis. They use carbon dioxide, water and sunlight. Metabolism in plants is constituted by photosynthesis, respiration and synthesis of organic compounds.
b) Kingdom Protista include protozoans that are autotrophic or heterotrophic in nature. These are eukaryotic organisms and most of the members are unicellular. Types of Protists are amoeboid protozoans, flagellated protozoans, ciliated protozoans and sporozoans.
c) Kingdom Animalia includes animals and multicellular eukaryotic organisms with the heterotrophic mode of nutrition, i.e. they depend on other organisms for food.
Note: Metabolic diversity refers to the variety of strategies adopted by various organisms to produce energy. Metabolic diversity evolved in prokaryotes first and then in eukaryotes. These pathways evolved as a result of interaction with the external environment and co-evolution.