The code below worked for me.
WebDriver Driver = new ChromeDriver();
Driver.manage().timeouts().implicitlyWait(30, TimeUnit.SECONDS);
//Driver.manage().window().maximize();
String url = "https://demoqa.com/automation-practice-form";
Driver.get(url);
WebElement products=Driver.findElement(By.id("subjectsInput"));
products.sendKeys("English");
products.sendKeys(Keys.ARROW_DOWN);
products.sendKeys(Keys.ENTER);