Hi Roughly4000BC!
A very apt username for this question
Since answer choice (A) uses the phrase "roughly" 4000 B.C., we don't need the passage itself to assert the tokens were made in 4000 B.C. specifically. The phrase "roughly" accounts for a similar degree of uncertainty as noted in the passage (some tokens before, some after) so that phrasing isn't reason enough to eliminate (A). In fact, like you mentioned, (A) is the correct answer so we definitely don't want to eliminate it!
Answer choice (D), on the other hand, overextends itself to an extent that the passage cannot support. By saying that these tokens showed a way in which a simple system "evolved into modern language", (D) goes beyond the text and cannot pass the Fact Test. Good job noting that!
I hope this helps!
Kate