select field with different key val options syntax

what is the syntax to set different key=value in select field options
as you can see in the screenshot the option key match the option’s value:

flameshot_screenshot

I’m looking to achieve something similar to this:

<select id="class" name="class" placeholder="select one" value="" class="thwepof-input-field">
<option value="">select one</option>
<option value="1">a</option>
<option value="2">b</option>
<option value="3">c</option>
</select>

The page I need help with: [log in to see the link]