Anna runs 4m/s east along a straight track, while Ben runs 6m/s east along the same track and passes her. Immediately after passing, Ben points a camera straight ahead at Anna. Which statement best describes Anna’s motion as recorded by Ben’s camera?
a) She moves backward relative to Ben at 6m/s.
b) She appears stationary relative to Ben.
c) She moves backward relative to Ben at 2m/s.
d) She moves ahead of Ben at 2m/s.