Please choose the correct ending to complete the given sentence: Assembling bicycle: A man is assembling a bike on a table. he

Ending1: is putting training wheels on the back wheel of the bike. Ending2: gets the bike ready, pushing it into motion. Ending3: explains some mechanics about the seat and torching. Ending4: is applying padding on the side.

Answer format: ending1/ending2/ending3/ending4