Question: Is the ingredient "graham cracker crumbs" optional in the recipe "Raspberry Chiffon Pie"?
SQL: SELECT T2.optional FROM Recipe AS T1 INNER JOIN Quantity AS T2 ON T1.recipe_id = T2.recipe_id INNER JOIN Ingredient AS T3 ON T3.ingredient_id = T2.ingredient_id WHERE T1.title = 'Raspberry Chiffon Pie' AND T3.name = 'graham cracker crumbs'