How do I disable (grey out) everything between div tags when a No is selected from a drop down

<h2> Clients Project Outcome Questionnaire </h2>
		<form method="post" name="theForm">  
		
		
		
		
		
		
		<table id="section_e">
		<tr><td class="headerblock" colspan="4">1  Achieve Economic Wellbeing </td></tr>
    	<td width="30">1a)</td>
        <td colspan="2">Did the client need support to maximise their income, including receipt of the correct welfare benefits?</td>
        <td><select id="1a_MaxIncome" name="1a_MaxIncome" class="need" onChange="Javascript:autoSubmit();">
        	
            	<option value="0" '; if ($q1a == '0') {echo ' selected="selected"';} echo '>Missing</option>
            
            	<option value="1" '; if ($q1a == '1') {echo ' selected="selected"';} echo '>Yes</option>
            
            	<option value="2" '; if ($q1a == '2') {echo ' selected="selected"';} echo '>No</option>
            
        </select></td>
    </tr>
    ';
	
	//Question 1a Result
	if ($q1a == '1')
	
  // If $qla is set to 1 (i.e. Yes) enable the content in the DIV tag
<div> //Start div tag
  echo '<tr>
    	<td></td>
    	<td class="userinfo" colspan="2">If No, please go to the next question - Question 1b)</td>
    </tr>
    <tr>
    	<td></td>
    	<td class="userinfo" colspan="2">If Yes, please continue</td>
    </tr>
    <tr>
    	<td></td>
     	<td colspan="2">Actual outcome for the client -<br />
        Has the client now maximised their income, including the receipt of the correct benefits?</td>
        <td><select id="Outcome_1a" name="Outcome_1a" class="outcome">
        	
            	<option value="0">Missing</option>
            
            	<option value="1">Yes</option>
            
            	<option value="2">No</option>
            
        </select></td>
	</tr>
	<tr>
    	<td></td>
    	<td colspan=2>If the outcome did not happen, please provide reasons:</td>
    </tr>
	<tr>
    	<td></td>   
    	<td>Main reason:</td>
		<td>'; 
		
		
		   // Create dropdown Support Need table lookup list
$queryreason1a = "SELECT spOutcomesID, type, description FROM outcomes_linktable tb2
LEFT OUTER JOIN outcome_categories tb3 ON tb2.id = tb3.id
WHERE spOutcomesQuestion = '1a'
ORDER BY spOutcomesID";

$resultreason1a = @mysql_query ($queryreason1a); // Run the query.

echo '<select id="Reason_1a_Primary" name="Reason_1a_Primary" class="reason">';

while($rowreason1a = mysql_fetch_array($resultreason1a, MYSQL_NUM))
{
echo '<option value="'.$rowreason1a[0].'">'.$rowreason1a[1].' -> '.$rowreason1a[2].'</option>';
}

echo '</select></td>
    </tr>
	<tr>
    	<td></td>
    	<td>Second reason (optional):</td>
        <td><select id="Reason_1a_Second" name="Reason_1a_Second" class="reason">';
$resultreason1a = @mysql_query ($queryreason1a); // Run the query.
while($rowreason1a = mysql_fetch_array($resultreason1a, MYSQL_NUM))
{
echo '<option value="'.$rowreason1a[0].'">'.$rowreason1a[1].' -> '.$rowreason1a[2].'</option>';
}

echo '</select></td>
    </tr>
	<tr>
    	<td></td>
    	<td>Third reason (optional):</td>
        <td><select id="Reason_1a_Third" name="Reason_1a_Third" class="reason">';
$resultreason1a = @mysql_query ($queryreason1a); // Run the query.
while($rowreason1a = mysql_fetch_array($resultreason1a, MYSQL_NUM))
{
echo '<option value="'.$rowreason1a[0].'">'.$rowreason1a[1].' -> '.$rowreason1a[2].'</option>';
}

echo '</select></td>
    </tr>';
 
	echo '</div> // end div tag

</table><hr />

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