Having in a source is bad because it really only offers one skewed opinion on the topic. bias credibility facts statistics

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.