Option D states that bacteria, micro-algae, and fungi are the most widely used microorganisms in industries. This statement is more comprehensive and accurate compared to the other options.

Bacteria: Bacteria are extensively used in various industries due to their diverse metabolic capabilities. They are employed in food production (e.g., fermentation processes, probiotics), pharmaceutical manufacturing (e.g., antibiotics production), waste treatment (e.g., wastewater treatment plants), and biotechnology (e.g., enzyme production, genetic engineering).

Micro-algae: Micro-algae, such as Chlorella and Spirulina, have gained attention in recent years for their potential applications in industries. They are utilized for the production of biofuels, nutritional supplements (rich in proteins, vitamins, and omega-3 fatty acids), pigments, and wastewater treatment.

Fungi: Fungi are utilized in several industrial processes. Yeast, a type of fungus, is widely used in baking and brewing industries for fermentation. Fungi are also employed in the production of antibiotics, enzymes, organic acids, and various secondary metabolites. In addition, certain fungi have applications in bioremediation and as biocontrol agents for agricultural purposes.

Therefore, option D correctly highlights the significant role of bacteria, micro-algae, and fungi as the most widely used microorganisms in industries, considering their various applications and contributions across different sectors.