Does C# support multiple-inheritance? No. Who is a protected class-level variable available to? It is available to any sub-class (a class inheriting this class). Are private class-level variables inherited? Yes, but they are not accessible. Although they are not visible or accessible via the class interface, they are inherited. Describe the accessibility modifier "protected internal". It is available to classes that are within the same assembly and derived from the specified base class. What's the top .NET class that everything is derived from? System.Object. What does the term immutable mean? The data value may not be changed. Note: The variable value may be changed, but the original immutable data value was discarded and a new data value was created in memory. What's the difference between System.String and System.Text.StringBuilder classes? System.String is immutable. System.StringBuilder was designed with the purpose of having a mutabl...