grey out dropdown box on selecting only one of the radio button
<p>I am new to javascripts, I am trying to modify codes on a form that includes radio button and dropdown menus, but I would like to grey out dropdown box on selecting only one of the radio button (electronic) selected.</p>

<p>Physical (radio button) 
Image (radio button)<br>
Electronic (radio button)</p>

<p>Number of Boxes       [dropdown box]<br>
I have 3 radio buttons above number of boxes (dropdown).  I want the dropdown selection box grayed out on selecting Electronic (radio button)</p>

<pre><code>&lt;input type="radio" name="radio" id="physical" value="physical"&gt;
              &lt;label for="physical"&gt;Physical&lt;br&gt;
                &lt;input type="radio" name="radio" id="image" value="image"&gt;
              Image               &lt;br&gt;
              &lt;input type="radio" name="radio" id="electronic" value="electronic"&gt;
              Electronic                  
</code></pre>

<p>I want this grayed out on selecting electronic above</p>

<pre><code>&lt;select name="NumberofBoxes" onchange="javascript:this.form.action='RecordsTransmittalForm.asp';this.form.submit();"&gt;
                    &lt;option value=""&gt;--select one--&lt;/option&gt;
                    &lt;%
                        for i = 1 to 100
                    %&gt;
                        &lt;%if clng(NumberofBoxes) = i then%&gt;
                            &lt;option value="&lt;%=i%&gt;" selected&gt;&lt;%=i%&gt;&lt;/option&gt;
                        &lt;%else%&gt;
                            &lt;option value="&lt;%=i%&gt;"&gt;&lt;%=i%&gt;&lt;/option&gt;
                        &lt;%end if%&gt;
                    &lt;%
                        next
                    %&gt;
                &lt;/select&gt;
</code></pre>
