Which of the variables below are accessible from o

Which of the variables below are accessible from other translation units?

int w = 1;
static int x = 2;
const int y = 3;
extern const int z = 4;

int main(int argc, char** argv)
{
    return 0;
}

Explanation

A name of file scope that is explicitly declared const, and not explicitly declared extern, has internal linkage, while in C it would have external linkage.
Rationale: Because const objects can be used as compile-time values in C++, this feature urges programmers to provide explicit initializer values for each const. This feature allows the user to put const objects in header files that are included in many compilation units.