JSFiddle - React, Tailwind, and code Playground

HTML

<select onchange="doOperation()" class="js-opt-a">
            <option value="default"> Start..</option>
                <option value="1"> 1</option>
                <option value="2"> 2</option>
                <option value="3"> 3 </option>
</select>
<select onchange="doOperation()" class="js-opt-b">
    <option value="default">Start...</option>
    <option value="4"> 4 </option>
    <option value="5"> 5 </option>
</select>

JavaScript

function doOperation() { /*whatever*/}
$(".js-opt-a").hide();
$(".js-opt-b").show();