What is meant by "beer engine"?

The term "beer engine" refers specifically to a hand-operated pump used to dispense beer, primarily from casks in a traditional pub setting. This device allows for a manual method of drawing beer, typically offering a more authentic and tactile experience for the server and the consumer. The beer engine works by creating a vacuum to draw the liquid from the cask and allow it to flow into the glass, which can enhance the natural carbonation and flavors of the beer, especially cask-conditioned ales.

While fermentation vessels, testing methods, and fermentation processes are all important components of brewing, they do not align with the definition of "beer engine." A beer engine is distinct in its function as a dispensing tool, making option B the correct interpretation. It reflects a classic brewing and serving technique that emphasizes the artisanal aspects of craft beer presentation.