What type of coffee is typically served as an Espresso?

Espresso is a specific brewing method that involves forcing hot water through finely-ground coffee under high pressure, resulting in a concentrated coffee beverage with a rich flavor and a layer of crema on top. This brewing technique differentiates espresso from other types of coffee, such as brewed coffee or drip coffee, which are made through different processes and typically have a different flavor profile and strength.

The options presented include various brewing methods or types of coffee. Cold brew refers to coffee that is steeped in cold water for an extended period, while drip coffee involves hot water gradually passing through coffee grounds in a filter. A dark roast simply describes the roast level of the coffee beans rather than the method used to brew them. Brewed coffee can encompass many brewing styles but does not accurately represent what is specifically defined as espresso.

Thus, the correct choice focuses on the distinctive method of preparing espresso, setting it apart from other options that do not apply to the definition or characteristics of espresso itself.