One of our discussion questions provided an example of the use of POSIX threads; a modified excerpt from it appears below. What pthread command would normally be used to force the main thread to wait for the termination of the thread that is created in the code. This is to be done within the context of pthreads. pthread t tidi, tid2; int main (void) int idi = 1, id2 = 2; int erri /* Create two threads to execute the run procedure. err = pthread create(&tidi, NULL, run, Sidi); if (err) { printf ("create of thread 1 failed. "); exit (1); } } O none of these Opthread_join O pthread_mutex O pthread_init O pthread_exit