Which of the following best describes the function of the first sentence of the second paragraph (lines 13–17) (reproduced below)?

The only notable thing about Arbour’s video is, perhaps, how dated it feels; while fat people still face daily harassment and systemic discrimination, body positive activists have gotten enough of a toehold in the public consciousness that, in 2015, most mainstream, non-anonymous media outlets at least have the decency to use coded language when they shame us.

It defends a previous claim by offering an example.
It previews the author’s line of reasoning in the larger argument.
It presents a fact that supports the opposing argument.
It clarifies a contentious term repeated throughout the passage.
It introduces different challenges faced by the writer in her daily life.