Please choose the correct ending to complete the given sentence: BMX: People are standing next to bmx bikes in an indoor field. the guys

Ending1: put their handlebars onto the bmx machine. Ending2: begin to take off the rims and put the kickstands down. Ending3: then mount their bikes behind the start line. Ending4: are playing a game of racquetball.

Answer format: ending1/ending2/ending3/ending4