Which Selenium Python code snippet correctly sets up a WebDriver instance for cross-browser testing based on a variable 'browser'?
Adriver = webdriver.FirefoxOptions()
if browser == 'chrome':
driver = webdriver.ChromeOptions()
Bif browser == 'firefox':
driver = webdriver.Firefox()
elif browser == 'chrome':
driver = webdriver.Chrome()
else:
driver = webdriver.Edge()
Cdriver = webdriver.Chrome()
if browser == 'firefox':
driver = webdriver.Firefox()
Ddriver = webdriver.Edge()
if browser == 'chrome':
driver = webdriver.Firefox()