Which of the following cheeses is commonly used in Quiche Lorraine?

Quiche Lorraine traditionally features Gruyère cheese due to its characteristic mild and nutty flavor that complements the other ingredients in the dish, such as eggs, cream, and bacon. Gruyère melts beautifully, creating a creamy and rich texture, which is essential for achieving the classic consistency of a quiche. Its distinctive taste adds depth to the quiche without overpowering the other flavors.

While Cheddar, Feta, and Parmesan are all delicious cheeses with their unique profiles, they do not align with the traditional preparation of Quiche Lorraine. Cheddar can be sharper and may change the overall flavor profile significantly. Feta has a tangy and crumbly texture, which could disrupt the smooth consistency of the quiche. Parmesan, while it can add a savory touch, is generally used more as a seasoning or garnish rather than as a primary ingredient. Thus, Gruyère stands out as the most suitable choice for this classic dish.