JSFiddle - React, Tailwind, and code Playground

HTML

<select id="one" onchange="reset(this)">
  <option></option>
  <option>Coffee</option>
  <option>Tea</option>
  <option>Espresso</option>
</select>
<select id="two" onchange="reset(this)">
  <option></option>
  <option>Milk</option>
  <option>Sugar</option>
  <option>Water</option>
</select>
<select id="three" onchange="displayResult()">
  <option></option>
  <option>One</option>
  <option>Two</option>
  <option>Three</option>
</select>

<div id="output"></div>

JavaScript

function reset(e) {
 var caller = e;
    if (caller.id === "one") {
        document.getElementById("two").value = 0;   
        document.getElementById("three").value = 0;
    } else {
        document.getElementById("three").value = 0;
    }
    
    displayResult();
}

function displayResult() {
    var one = document.getElementById("one");
    var valueOne = one.selectedIndex != -1 ? (one.options[one.selectedIndex].value) : "";
    
    var two = document.getElementById("two");
    var valueTwo = two.selectedIndex != -1 ? (two.options[two.selectedIndex].value) : "";
    
    var three = document.getElementById("three");
    var valueThree = three.selectedIndex != -1 ? (three.options[three.selectedIndex].value) : "";
    
    document.getElementById("output").innerHTML = "";
    document.getElementById("output").innerHTML = "<p>Dropdown one:\n" + valueOne + "</p>";
    document.getElementById("output").innerHTML += "<p>Dropdown two:\n" + valueTwo + "</p>";
    document.getElementById("output").innerHTML += "<p>Dropdown three:\n" + valueThree + "</p>";
}