What is the most logical next event?

A drum corp is heard drumming proudly as the cadets march down the street. The marchers begin waving to the crowd and greeting the onlookers. a long train whistle

Available choices:
1). plays behind them as the little girl in green returns to her position.;
2). is blown to signal it of a boarding.;
3). wakes up the crowd.;
4). is heard as the cadets continue to wave to the crowd.;
4).