What is the output of this program?

#include<stdio.h>
#include<pthread.h>
 
void *fun_t(void *arg);
void *fun_t(void *arg)
{
    int ret;
    ret = pthread_exit("Bye");
    printf("%d\n",ret);
}
int main()
{
    pthread_t pt;
    void *res_t;
    if(pthread_create(&pt,NULL,fun_t,NULL) != 0)
        perror("pthread_create");
    if(pthread_join(pt,&res_t) != 0)
        perror("pthread_join");
    return 0;
}

A. 0

B. 1

C. -1

D. none of the mentioned

Answer: Option D