Which functions can be used as function pointer callback argument

A function, process, processes the given data and calls the callback function pointer with completion status:

void process(const char* data, void(*callback)(bool)) {
  // ... process data and call callback with completion status
  callback(true);
} 

We have declaration of struct Store and a stand-alone function onProcessed:

struct Store {
 void onProcessed(bool status);

 static void onProcessedStatic(bool status); 
};

void onProcessed(bool status); 

Select all of which that can be used as callback argument for function process: