You should take the train instead of the bus.

-> If

How does national geographic allow subjectivity and bias to appear in its video about the flu? a. it uses second-person narration to make the viewer feel guilty for not getting a flu shot. b. it uses the testimonial of a doctor who feels very strongly that all americans should be vaccinated. c. it includes an advertisement for an over-the-counter flu medication. d. it uses onminous music and a blue filter to make the video more frightening.