The bridge is wood , 2X4 's spaced just far enough apart that the ride in the stroller was pretty bumpy , which is why he quieted . So , we went to Tim Horton 's in Mack 's building for breakfast , which was good . Then Owen and I walked home . He was quiet the whole way , but woke up as I arrived home .

Generate a question about the above context.
Why did the bumpy ride cause him to quieten ?
Available choices: (1). he could n't complain anymore because he could n't speak over the bumpiness; (2). He fell asleep because the bumpiness acted as a rocker for him and rocked him to sleep; (3). the bumpiness made him feel nauseous so he was quiet as a result; (4). he was so upset about the bumpiness that he tried to be quiet and ignore it;