In 1968, chemist Spencer Silver attempted to create a super-strong adhesive but accidentally developed a low-tack, reusable pressure-sensitive adhesive instead. Years later, his colleague Art Fry ______ using the adhesive to anchor his bookmark in his hymnbook, giving birth to the Post-it Note.

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Which choice completes the text so that it conforms to the conventions of Standard English?

A

proposed

B

proposes

C

has proposed

D

is proposing

Correct Answer: A

Choice A is the best answer. The sentence narrates a sequence of events in the past ("Years later..."). The simple past tense "proposed" is consistent with the historical context established by "attempted" and "developed" in the previous sentence.