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 err; / Create two threads to execute the run procedure. */ err = pthread_create(&tidl, NULL, run, Gidl); if (err) printf ("create of thread 1 failed. "); exit (1); O pthread_exit O pthread_mutex O pthread_join O pthread_init none of these