Right option is (a) Water content between 55%-75%
The explanation: Water content between 55%-75% is the most suitable for dry fermentation process with different moisture content for fermentation in the fermenters under anaerobic processing, whereas, Water content between 0%-15% is very dry and the solid wastes cannot be processed by dry fermentation process of anaerobic digestion, water content between 85%-95% and water content between 80%-85% is usually categorized as wet fermentation.