#include&lt;stdio.h&gt;   #include&lt;sys/types.h&gt;   #include&lt;sys/socket.h&gt;&nbsp;   int main&#40;&#41;   &#123;       struct sockaddr_in addr;       int fd;       fd = socket&#40;AF_INET,SOCK_STREAM,0&#41;;       printf&#40;&quot;%d\n&quot;,fd&#41;;       return 0;   &#125;
A. -1
B. 3
C. error
D. none of the mentioned
Answer:A
#include&lt;stdio.h&gt;   #include&lt;sys/types.h&gt;   #include&lt;sys/socket.h&gt;&nbsp;   int main&#40;&#41;   &#123;       struct sockaddr_in addr;       int fd;       fd = socket&#40;AF_INET,SOCK_STREAM,0&#41;;       printf&#40;&quot;%d\n&quot;,fd&#41;;       return 0;   &#125;
A. -1 B. 3 C. error D. none of the mentioned
Explanation:The header file netinet/in.h is required to use the structure sockaddr_in.