Free dynamic memory with free() : <pre><code>#include &lt;stdlib.h&gt;
#include &lt;stdio.h&gt;
int main() {
    char **last_names;
    // last_names has been assigned a char * array of length 4. Each element of the array has
    // been assigned a char array of length 20.
    //
    // All of these memory has been allocated on the heap.
    // Free all of the allocated memory (hint: 5 total arrays).


    return 0;
}
</code></pre>

<p>I know the free() method and this is my approach;</p>

<pre><code>free(*last_names);
free(last_names);
</code></pre>

<p>but it's not true.  Any help will be appreciated</p>
