When choosing between interfaces and abstract classes, it's important to understand their purposes. Interfaces are ideal when you expect that unrelated classes would implement the interfaces, as they provide a way to specify a set of methods that must be implemented without dictating how the methods should be used (Option B). Additionally, interfaces are suitable when you want to take advantage of multiple inheritance of type, since a class can implement multiple interfaces but can only extend one abstract class (Option E). These two scenarios highlight the flexibility and design patterns that interfaces offer over abstract classes.