GMAT Critical Reasoning (CR) | Re: A newly discovered painting on wooden panel by Michelangelo

I got B, which makes sense. I am just curious about another assumption I had in mind, which isnt one of the answer choice, but given the initial argument, I want to understand if the assumption I formulated is correct.

Original statement: ...o must have been completed after 1507 but before 1509.
Assumption: That the coin that was minted in 1507 could not have been used during 1507 to complete the painting.
The situation I am proposing is: The coin of 1507 would have been available in 1507. Can
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