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<html><body><select id="mySelect"> <option>Apple</option> <option>Orange</option> <option>Pineapple</option> <option>Banana</option></select><p>Click the button to deselect options.</p><button onclick="myFunction()">Try it</button><script>function myFunction() { document.getElementById("mySelect").selectedIndex = "-1";}</script></body></html>