Which pattern?

Which of the following Regex patterns results in the following text?

>>> my_string = "Let's write RegEx!"
>>> re.findall(PATTERN, my_string)
['Let', 's', 'write', 'RegEx']

In the IPython Shell, try replacing PATTERN with one of the below options and observe the resulting output. The re module has been pre-imported for you and my_string is available in your namespace.