JSFiddle - React, Tailwind, and code Playground
HTML
<div id="question-1" class="top-question">
What do you want?<br>
<select>
<option value='thing'>thing</option>
<option value='item'>item</option>
</select>
<div id="question-1a" class="sub-question">
How many of them?<br>
<select>
<option value='5'>five</option>
<option value='10'>ten</option>
</select>
</div>
</div>
JavaScript
$('.sub-question').hide()
$('.top-question').bind('change',function(){
$('.sub-question').show()
})