JSFiddle - React, Tailwind, and code Playground

HTML

A:
<select id="inputsa">
    <option id="inputa" name="input[1][]">A</option>
    <option id="inputb" name="input">B</option>
    <option id="inputc" name="input[2][]">C</option>
</select>B:
<select id="inputsb">
    <option id="inputa" name="input[1][]">D</option>
    <option id="inputb" name="input">E</option>
    <option id="inputc" name="input[2][]">F</option>
</select>C:
<select id="inputsc">
    <option id="inputa" name="input[1][]">G</option>
    <option id="inputb" name="input">H</option>
    <option id="inputc" name="input[2][]">I</option>
</select>
<br>
<input id="copyAtoB" type="button" value="Copy A to B" onclick="functionCopyAtoB();">
<br>
<input id="copyBtoC" type="button" value="Copy B to C" onclick="functionCopyBtoC();">

JavaScript

function functionCopyAtoB() {
        $('#inputsb').val($('#inputsa').val());
    }

    function functionCopyBtoC() {
        $('#inputsc').val($('#inputsb').val());
    }