How do access modifiers affect the Overriding process? Can you make an overridden method more restrictive?

Access modifiers are part of the substitutability contract of an overridable method. An overriding method generally cannot reduce the visibility of the base method because code using the base type must retain the access guaranteed by that base contract. For example, a public method cannot normally be overridden as protected or private. In Java, an override can maintain or increase visibility, while C# requires the override to use compatible accessibility with the virtual/abstract base member.