I got this question right, because I knew “trifling” was a much better fit than “obvious” for blank 1. Therefore, the combination must be “trifling” and “incomplete.” But if you were exploring double possibility the other possibility could be “obvious” and “credible” OR “Obvious” and “extant”. Greg immediately ruled out extant - but why? Extant means to still exist which makes sense also. I want to understand why that option was ruled out - would appreciate input here!
“Incomplete” directly addresses the issue of gaps, ie if much of the documentary evidence is incomplete, significant gaps exist.
“Credible” and “extant”, on the other hand, describe other properties of the evidence ie, its reliability and its continued existence, respectively.
Neither tells us whether the evidence is complete or incomplete which is what matters here.
Evidence can be credible yet incomplete, or extant yet incomplete.
“Trifling/Incomplete” creates a better, sharper causal relationship necessitated by “since”.
Thank you for this! Had a follow up question for you - Greg doesn’t eliminate “credible” though initially. He specifically eliminates “extant” right off the bat though. Is it because “existing” existing doesn’t tell us about gaps nearly as much as “credible” or “incomplete”?