从选择下拉菜单中选择一个选项后，如何更改该选项的字体颜色？

select option {
  color: #ff0000; /* 这里设置为红色，可以根据需要更改颜色数值 */
}

select option:nth-child(1) {
  color: #ff0000;
}

select option:nth-child(2) {
  color: #0000ff;
}

select option:nth-child(3) {
  color: #00ff00;
}

<select onchange="changeOptionColor(this)">
  <option value="red">红色</option>
  <option value="blue">蓝色</option>
  <option value="green">绿色</option>
</select>

function changeOptionColor(selectElement) {
  var selectedValue = selectElement.value;
  
  switch (selectedValue) {
    case 'red':
      selectElement.style.color = '#ff0000';
      break;
    case 'blue':
      selectElement.style.color = '#0000ff';
      break;
    case 'green':
      selectElement.style.color = '#00ff00';
      break;
    default:
      selectElement.style.color = '#000000';
  }
}