What technique should a server use to reduce foam while pouring beer?

Pouring beer down the side of the glass is an effective technique to reduce foam because it allows the beer to flow gently into the glass rather than splashing directly into the center. This method minimizes the turbulence as the beer enters the glass, which is a key factor that helps in controlling the amount of foam produced during pouring.

When beer is poured with force or directly into the center, it can create a significant amount of agitation, leading to a larger head of foam. Pouring it down the side creates a more gradual introduction to the glass, thereby reducing the likelihood of excessive foaming. This technique is especially important for certain styles of beer where a controlled amount of head is preferred for optimal aroma and taste.

While the other options, such as using a warmer glass or pouring from further away, might influence the pouring process, they are not as directly effective at minimizing foam compared to the method of pouring down the side.