Using the information given below, answer the question: A chef is trying a recipe for a tasty ice cream using four ingredients. He can choose from three liquids for taste, labeled A, B and C, which are stable in nature, and the choice for flavor can be from four liquids labeled W, X, Y and Z. For the new ice cream recipe to be tasty, there must be two liquids from the taste giving liquids (A, B, C) and two liquids from the flavor giving liquids (W, X, Y, Z). Also, certain liquids cannot be mixed because of reactions that make the mix unhealthy for human consumption: B cannot be mixed with W, C cannot be mixed with Y, and Y cannot be mixed with Z.
If the chef calculated that Y is the most important flavor and must be used in the recipe, which other ingredients must be part of the recipe?