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<html><body><select id="mySelect" size="1"> <option>Cat</option> <option>Dog</option> <option>Horse</option> <option>Elephant</option> <option>Mouse</option> <option>Fish</option> <option>Cow</option></select><p>Click the button to change the number of visible options in the dropdown list.</p><button onclick="myFunction()">Try it</button><script>function myFunction() { document.getElementById("mySelect").size = "4";}</script></body></html>