Syntax Correction for Drop Down List Selection

I have generated a drop down list with php but I can't seem to set the selected value. Could someone please correct my mistake.
I have attached the code.

Thanks

$dataset = array("January","February","March","April","May","June","July","August","September","October","November","December");
 
$test = "January";
echo "<select name=vendorddl>";
echo "<option value="."---".">"."---"."</option>";
$numberofrecords = count($dataset);	
	for ($x=0; $x<$numberofrecords; $x++)
	{
		$selected = $test;
	    $lbvalue = $dataset[$x];
		echo "<option value=".$lbvalue."selected="."'".$selected."'".">".$lbvalue."</option>";
		
	}
echo "</select>";// Closing of list box

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