9. The writer is considering deleting sentence 11 (reproduced below).
Unsurprisingly, teens overwhelmingly describe themselves as tired during the day, according to sleep experts Wolfson and Carskadon.

Should the writer keep or delete sentence 11?

- Keep it, because the anecdotal evidence from teenagers confirms the accuracy of the CDC's evidence.
- Keep it, because it includes both personal observations and a reliable source to support the claim.
- Delete it, because personal observations are insufficient evidence for a claim of value such as this one.
- Delete it, because the first half reads like an opinion statement that does not enhance the claim.
- Delete it, because it lacks quantitative evidence and therefore does not sufficiently support the claim.

I've also included the whole reading for context (it might help)