Best way to implement globally scoped data

I'd like to make program-wide data in a C++ program, without running into pesky LNK2005 errors when all the source files #includes this "global variable repository" file.

I have 2 ways to do it in C++, and I'm asking which way is better.

The easiest way to do it in C# is just public static members.

C#:

public static class DataContainer
{
    public static Object data1 ;
    public static Object data2 ;
}

In C++ you can do the same thing

C++ global data way#1:

class DataContainer
{
public:
    static Object data1 ;
    static Object data2 ;
} ;
Object DataContainer::data1 ;
Object DataContainer::data2 ;

However there's also extern

C++ global data way #2:

class DataContainer
{
public:
    Object data1 ;
    Object data2 ;
} ;
extern DataContainer * dataContainer ; // instantiate in .cpp file

In C++ which is better, or possibly another way which I haven't thought about?

The solution has to not cause LNK2005 "object already defined" errors.