Please choose the correct ending to complete the given sentence: Assembling bicycle: The front of a building called giant is seen. technicians

Ending1: are using welding tools to hammer a piece of metal down. Ending2: are seen stepping on boards and washing the inside. Ending3: are shown inside, working on bicycles. Ending4: are inside cleaning up the exterior and roof.

Answer format: ending1/ending2/ending3/ending4