Introduction:
In the production of beverages, various microorganisms are utilized for their ability to ferment sugars and produce desirable flavors and textures. One such organism commonly used is Saccharomyces cerevisiae, also known as brewer's yeast.

Explanation:
Saccharomyces cerevisiae:
- Saccharomyces cerevisiae is a type of yeast that ferments sugars and converts them into alcohol and carbon dioxide through a process called alcoholic fermentation.
- This organism is commonly used in the production of alcoholic beverages such as beer, wine, and spirits.
- The yeast cells consume sugars present in the beverage ingredients, such as malted barley in beer or grapes in wine, and produce alcohol as a byproduct.
- The presence of Saccharomyces cerevisiae is essential for the fermentation process, which gives beverages their characteristic flavors, aromas, and alcohol content.

Other options:
- Penicillium notatum: Penicillium notatum is a type of mold commonly used in the production of antibiotics, such as penicillin. It is not used in the production of beverages.
- Aspergillus niger: Aspergillus niger is a type of fungus that is commonly used in the production of citric acid and enzymes. It is not used in the production of beverages.
- Clostridium butyricum: Clostridium butyricum is a type of bacteria that produces butyric acid. It is not used in the production of beverages.

Conclusion:
The correct answer is option 'B' - Saccharomyces cerevisiae. This yeast organism is widely used in the production of various alcoholic beverages due to its ability to ferment sugars and convert them into alcohol and carbon dioxide. It plays a crucial role in the fermentation process, which gives beverages their desired flavors, aromas, and alcohol content.