Passage Summary: A customer got bad photos back. The camera and film were fine, so the argument says that if the customer didn't mess up, the store must have and should pay her back.

Conclusion: If the customer's claim of handling the film correctly is true, then the store is obligated to provide a refund.

Reasoning: The photographs were unsatisfactory, and neither the film nor the camera was defective. Since a store owes a refund if they process pictures improperly, the store must be at fault if the customer isn't.

Analysis: This argument relies on a process of elimination that isn't quite complete. It assumes that if the equipment was fine and the customer was careful, the only remaining possibility is that the store messed up the processing. To bridge this gap, we need to assume there aren't other 'wild card' factors that could ruin photos besides the customer, the equipment, or the store. Look for an answer that confirms the store's processing is the only other variable that could result in unsatisfactory photos.