#include&lt;stdio.h&gt;   #include&lt;pthread.h&gt;&nbsp;   int a;     void *fun_t&#40;void *arg&#41;;   void *fun_t&#40;void *arg&#41;   &#123;              a = 20;       pthread_exit&#40;&quot;Bye&quot;&#41;;   &#125;   int main&#40;&#41;   &#123;       pthread_t pt;       void *res_t;       a = 10;               if&#40;pthread_create&#40;&amp;pt,NULL,fun_t,NULL&#41; != 0&#41;           perror&#40;&quot;pthread_create&quot;&#41;;       if&#40;pthread_join&#40;pt,&amp;res_t&#41; != 0&#41;           perror&#40;&quot;pthread_join&quot;&#41;;       printf&#40;&quot;%d\n&quot;,a&#41;;       return 0;   &#125;
A. 10
B. 20
C. segmentation fault
D. none of the mentioned
Answer:A
#include&lt;stdio.h&gt;   #include&lt;pthread.h&gt;&nbsp;   int a;     void *fun_t&#40;void *arg&#41;;   void *fun_t&#40;void *arg&#41;   &#123;              a = 20;       pthread_exit&#40;&quot;Bye&quot;&#41;;   &#125;   int main&#40;&#41;   &#123;       pthread_t pt;       void *res_t;       a = 10;               if&#40;pthread_create&#40;&amp;pt,NULL,fun_t,NULL&#41; != 0&#41;           perror&#40;&quot;pthread_create&quot;&#41;;       if&#40;pthread_join&#40;pt,&amp;res_t&#41; != 0&#41;           perror&#40;&quot;pthread_join&quot;&#41;;       printf&#40;&quot;%d\n&quot;,a&#41;;       return 0;   &#125;
A. 10 B. 20 C. segmentation fault D. none of the mentioned
Explanation:In this program the value of variable “a” is changed by the thread “fun_t”.