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<!DOCTYPE html> <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>