public class ClassA
{
    public virtual object GetObject()
    {
        var type = new StackTrace(0).GetFrame(1).GetMethod().DeclaringType;
        return Activator.CreateInstance(type == typeof(Program) ? typeof(ClassA) : type);
    }
}

public class ClassB : ClassA
{
    public override object GetObject()
    {
        return base.GetObject();
    }
}

public class ClassC : ClassA
{
    public override object GetObject()
    {
        return base.GetObject();
    }
}

[MethodImpl(MethodImplOptions.NoInlining)]