Событие для <option> , изменить шрифт текста с <option>

var sel = document.querySelector('select'); 
//---------------------------------------------------------------- 
// No click only onchange event  
sel.addEventListener('change', function (e) {  
  if(sel.value == 'Audi'){ 
  // do what you need here 
   console.log('Doing....... ' + sel.value); 
  } 
  console.log('Changed ', sel.value); 
})

<select id="mySelect"> 
  <option value="Audi">Audi 
  <option value="BMW">BMW 
  <option value="Mercedes">Mercedes 
  <option value="Volvo">Volvo 
 </select>

select#mySelect { 
  color: red; 
} 
 
select#mySelect option:not(:checked) { 
  color: black; 
} 
 
select#mySelect2 option:checked { 
  color: red; 
}

<select id="mySelect"> 
  <option value="Audi">Audi</option> 
  <option value="BMW">BMW</option> 
  <option value="Mercedes">Mercedes</option> 
  <option value="Volvo">Volvo</option> 
</select> 
 
<select id="mySelect2"> 
  <option value="Audi">Audi</option> 
  <option value="BMW">BMW</option> 
  <option value="Mercedes">Mercedes</option> 
  <option value="Volvo">Volvo</option> 
</select>