The correct answer is EXTENDED METAPHOR. Extended metaphor refers to a comparison between two things that are not alike, which continues throughout a series of sentences in a paragraph or in lines of poem. It is also called sustained metaphor and authors usually use it in order to create a clear comparison between two things.
Answer: It is number 2 In a population-based sample of 5-to 17-year-olds, 70 percent of obese youth had at least one risk factor for cardiovascular disease