How to select random options in multiple select dropdown box and print them

WebDriver driver=new FirefoxDriver();

driver.get("https://www.facebook.com/");

WebElement day=driver.findElement(By.id("day"));

Select sel=new Select(box);

sel.selectByIndex(0);

sel.selectByIndex(1);

sel.selectByIndex(2);

List<WebElement>list=sel.getAllSelecetedOptions();

System.out.println(list.size());