<human>: Here is a goal: What ingredients are used to make a simple royal icing?

How would you accomplish this goal?

OPTIONS:
- Powdered sugar, whole milk or water, and egg yolks are the ingredients used to make royal icing.
- Powdered sugar, whole milk or water, and egg whites are the ingredients used to make royal icing.
<bot>: Powdered sugar, whole milk or water, and egg whites are the ingredients used to make royal icing.