prova così

codice:
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<title>option red</title>
<style type="text/css">
.red {
	color: #F00;
}
</style>
</head>

<body>
<select name="test">
	<option value="1">111</option>
	<option value="2">222</option>
	<option value="3" class="red">333</option>
	<option value="4">444</option>
	<option value="5">555</option>
</select>
</body>
</html>