You are developing a custom-collection class.You need to create a method in your class. You need to ensure that the method you create in your class returns a type that is compatible with the Foreach statement. Which criterion should the method meet？（）

A. The method must return a type of either IEnumerator or IEnumerable.
B. The method must return a type of IComparable.
C. The method must explicitly contain a collection.
D. The method must be the only iterator in the class.