The New Wiper Blades<br>Mary was having trouble seeing out of her windshield. Her wiper blades weren't working properly. Mary stopped at a car parts store. She found the proper sized blades. Mary bought the blades and installed them on her car.
Mary drove to a car parts store. 
The text says Mary stopped at a car parts store - not how she got there. Not sure why the model thought the statement was incorrect, though. Maybe it thought the car was broken?