What is the aroma associated with hydrogen sulfide (H2S) in beer?

Hydrogen sulfide (H2S) in beer typically emits an aroma that is sulfuric and reminiscent of rotten eggs. This distinctive scent is a result of H2S being produced during fermentation, particularly under conditions of yeast stress, such as nutrient deficiency or when yeast are improperly handled. The presence of this compound is often considered a flaw in beer due to its unpleasant nature, so brewers strive to minimize its levels during production.

The other aromas listed in the other choices do not accurately describe H2S. Fruity and floral notes are typically associated with esters produced by yeast fermentation but are distinct from the pungent sulfur aromas. Earthy and grassy aromas are more reflective of certain hop varieties or grains, while nutty and caramel notes are often the result of specific malt characteristics, neither of which resemble the characteristic smell of hydrogen sulfide.