Question

identifying causes and effects
fry remembered a curious adhesive – a strong and yet easily removed “unglue”– that spencer silver, another 3m researcher, had come upon several years earlier. . . . silver felt the unusual adhesive might have some commercial value, and so he demonstrated it to various colleagues, including fry. at the time, no one had come up with a use for it, and so the formula for the weak adhesive was filed away – until the monday morning when fry came to work with the idea of making sticky bookmarks that could also be removed without damaging the book.
—the evolution of useful things, henry petroski
why was spencer silver’s work an essential part of fry’s invention?
○ he worked alongside fry on the sticky notes.
○ he convinced other people to believe in fry’s invention.
○ he told fry about the “unglue” that he had discovered.
○ he came up with a commercial use for the “unglue.”

Explanation:

The text states that Fry remembered the "unglue" (adhesive) that Silver had discovered. This adhesive was crucial for Fry's invention of sticky bookmarks (which led to sticky notes). The first option is wrong as the text doesn't say they worked side - by - side. The second option is incorrect as there's no mention of Silver convincing others about Fry's invention. The fourth option is wrong because it was Fry who came up with the commercial use (sticky bookmarks/notes), not Silver.

Answer:

He told Fry about the "unglue" that he had discovered.