All three statements accurately describe the nutritional diversity found in bacteria:

Statement (I) is True: Bacteria exhibit the most extensive metabolic diversity of any group of organisms, utilizing both autotrophic (self-feeding) and heterotrophic (relying on others) modes of nutrition.

Statement (II) is True: While the majority of bacteria are heterotrophic, a significant number are autotrophic. These autotrophs are subdivided into photosynthetic autotrophs (use light energy, like cyanobacteria) and chemosynthetic autotrophs (use chemical energy from inorganic substances).

Statement (III) is True: Heterotrophic nutrition is defined by the inability of an organism to synthesize its own food; instead, it must obtain ready-made organic food from external sources such as other organisms or dead organic matter.

──────────────────────────────────────────────────────────────────────────────────────────