Match each line of code to the best description 1: pthread_cond_signal 2: pthread_mutex_unlock 3: pthread_join 4: pthread_mutex_lock 5: pthread_cond_wait匹配题

the calling thread attempts to enter a critical section, blocks if another thread is inside and lock isn't free

the calling thread waits (suspends its execution) until a condition is true: another thread will signal it to wake up

sends a signal to wake a thread that is waiting (suspended) on a condition to be true

the calling thread waits (suspends its execution) until the target thread terminates

the calling thread exits a critical section, thus allowing other threads to enter