function argument passing
<p>Given that 'fn' is a function for which the below code compiles and runs properly</p>

<pre><code>  int main(){
       char x = 0;
       fn(x + 1);
       fn(++x);
    }
</code></pre>

<p>Which of these is not a likely declaration of 'fn'? which one I should choose b or c and why?? </p>

<pre><code>b) fn(int &amp; rx); 
c) fn(int const&amp; rcx);
</code></pre>
