C. by demonstrating that researchers and experts agree with the author’s point of view
The author uses the voices of credible figures, such as Atul Upadhyay from a global health organization and Professor Sarah Hawkes from UCL, to support the claim that junk food consumption among children is a serious issue. This appeals to ethos by showing that recognized experts in the field share concerns about the impact of junk food on children's health, thereby reinforcing the author's argument.