What is a characteristic of low attenuative yeast strains?

Low attenuative yeast strains are characterized by high flocculence. Flocculence refers to the tendency of yeast cells to clump together and settle to the bottom of the fermentation vessel after fermentation is complete. This characteristic benefits the brewing process, as it makes the separation of yeast from the beer more efficient, leading to clearer beer.

Low attenuative strains don't ferment all the available sugars in the wort, which means they typically leave a higher residual sugar content, contributing to the sweetness and body of the beer. This trait also affects their alcohol production, fermentation speed, and overall attenuation rates. High attenuation rates are indicative of yeast that fully consumes sugars, which contrasts with the behavior of low attenuative strains. Fast fermentation is also associated with yeast strains that efficiently convert sugars into alcohol, which again is not a characteristic of low attenuative strains.

Thus, high flocculence is the primary defining trait of low attenuative yeast strains, making this the correct answer.