9. C
Question Type: Identification (27 - 29)
Identification questions test whether we can use our fingers to point to answers in the passage. Here, we’re asked to find the answer to questions posed by the answer choices. (C) asks, "When were optical storage disks a state-of-the-art storage medium?" Lines 27-29 provide the answer: in the 1980s optical computer disks were on "the cutting edge of technology."
(A) The third paragraph mentions these works, but it never discusses whether they were printed on parchment.
(B) Paragraph 1 tells us acid paper is unstable, but not why. Moreover, Paragraph 2 does not discuss why storage tape lasts only ten years.
(D) Paragraph 1 says clay tablets are in museums around the world, but it does not mention how many of them survive
(E) Paragraph 3 discusses found works of Plato, but it does not mention how they were originally written.