What does "muddy sake" refer to?

"Muddy sake" refers to Nigori sake, which is not fully filtered. This type of sake retains some of the rice lees (the sediment that forms during fermentation), resulting in a cloudy appearance, which can be reminiscent of mud. The presence of these lees gives Nigori sake a creamy texture and often a sweeter flavor profile compared to fully filtered sake. This characteristic is a defining feature of Nigori sake, distinguishing it from other types that undergo complete filtration, leading to a clear and polished appearance.

The other choices describe different aspects of sake but do not align with the description of "muddy sake." Filtered sake is clear and smooth, sake with added flavorings would typically not be referred to in this way, and intensely aged sake might possess complex flavors and aromas but does not imply a cloudy appearance.