Preventing further overrides in C#.NET — which modifier stops virtual inheritance (no further overriding) in a derived class?

Introduction / Context:
Sometimes a derived class wants to stop the override chain. C# provides a modifier for this purpose.

Concept / Approach:
Use sealed on an override (sealed override) to prevent further overriding down the inheritance chain.

Why Other Options Are Wrong:
They are not C# modifiers applicable to method overriding.

Final Answer:
sealed