Linux Debugging Interview Question:

What is the output of this program no 4?
#include<stdio.h>
#include<pthread.h>

int a;
void *fun_t(void *arg);
void *fun_t(void *arg)
{
a = 20;
pthread_exit("Bye");
}
int main()
{
pthread_t pt;
void *res_t;
a = 10;
if(pthread_create(&pt,NULL,fun_t,NULL) != 0)
perror("pthread_create");
if(pthread_join(pt,&res_t) != 0)
perror("pthread_join");
printf("%dn",a);
return 0;
}
a) 10
b) 20
c) segmentation fault
d) none of the mentioned