Which does not represent a change in velocity?
Group of answer choices

A person is riding a bicycle at 4 m/s west and decreases her speed to 3 m/s.

A plane is flying south at 600 km/h and then flies directly upwards before returning to the airport.

A balloon is floating up into the air at 1 m/s.

A bus is traveling west at 2 m/s and then turns a corner.