Extreme programming expresses user requirements as stories, with each story written on a card. Identify which of the following are considered the advantages of this approach to the requirements description. $($Select all that apply$)$

Group of answer choices

They are liable to be incomplete and their informal nature makes this incompleteness difficult to detect.

They represent real situations that commonly arise so the system will support the most common user operations.

They focus on functional requirements rather than non$-$functional requirements.

It is easy for users to understand and critique the stories.