<!DOCTYPE html>
<html>
<head>
<style>
option:disabled {
background: red;
}
</style>
</head>
<body>
<select>
<option value="volvo">Volvo</option>
<option value="saab" disabled>Saab</option>
<option value="opel">Opel</option>
<option value="audi" disabled>Audi</option>
<option value="bmw">BMW</option>
</select>
</body>
</html>