What additional ingredient is found in the Bechamel sauce?

Bechamel sauce, one of the five mother sauces of classical French cuisine, is primarily made from a roux (which is a mixture of flour and fat) and milk. The role of milk is crucial as it gives Bechamel sauce its creamy texture and smooth consistency. This sauce is often used as a base for various other sauces and dishes, such as lasagna or macaroni and cheese. Milk not only contributes to the flavor but also provides the necessary liquid to create the sauce, making it a fundamental ingredient. The other options, while they may be components of different sauces or dishes, do not form part of the traditional Bechamel sauce recipe.