(1) Rupert and Deb ran out of gas on their way to the concert. (2) Rupert spent twenty minutes trying to get help before he suggested they walk the three miles to the gas station in halloway. (3) When they arrived at the gas station, Rupert was shocked. (4) He had left his wallet back in the car and didn't have change to make a phone call.
Which sentence contains a capitalization error?