7. (2 points) Where to declare a variable called counter' that can be seen by al worker threads, in the following piece of code [CODE FOR QUESTION 7] #include #include void worker (void &arg) f b) *worker logic* int main(void) ( I C) pthreadt tidl. tid2 pthread_create(&tid1, NULL. worker NULL) pthread_create(&tid2. NULL. worker NULL): d) pthreadjoin(tid1, NULL) pthread_join(tid2, NULL) return 0