Debugging Question:

This program is valid for
#include<stdio.h>
#include<netinet/in.h>
#include<sys/types.h>
#include<sys/socket.h>

int main()
{
int fd_client,fd, len;
struct sockaddr_in add_server;
fd_client = socket(AF_INET,SOCK_STREAM,0);
if (fd_client == -1){
perror("fd_sock");
exit(1);
}
add_server.sin_family = AF_INET;
add_server.sin_port = ntohs(4001);
add_server.sin_addr.s_addr = inet_addr("144.29.8.2");
len = sizeof(add_server);
fd = connect(fd_client,(struct sockaddr*)&add_server,len);
return 0;
}

a) IPv4
b) IPv6
c) both (a) and (b)
d) none of the mentioned