In the "underlying reasons 'urtclear" section of "yes, sitting too long can kill you, even if you exercise," how does the
author develop the idea that experts are not sure why sitting for so long can hurt you?

a. in the section, the author contrasts two experts who have different opinions of the study and then allows readers to infer the central idea.

b. the author states the central idea in a sentence at the beginning of the section and then supports
it with narratives about people with different health outcomes.

c. the author states the central idea in a heading and then in the section provides details about
multiple possible causes.

d. the author provides many contradictory details in the section and then concludes it by
summarizing the central idea.