Question

researchers have long debated the origins of silver used in european coins from the 600s through the early 800s ce. geochemical analysis by kershaw et al. of 49 coins dating to 660 - 820 ce provides concrete evidence that reconciles two competing theories: early coins were made from byzantine silver, and later coins used frankish silver, findings that provide firm details in a previously ______ area of study.
which choice completes the text with the most logical and precise word or phrase?
a. esoteric
b. authoritative
c. solitary
d. speculative

Explanation:

The context is about a previously unclear (due to debate) area of study (origins of silver in European coins). The geochemical analysis provides "firm details", which contrasts with the prior state. "Speculative" means based on guesswork rather than firm evidence. Since before the analysis, it was a debated (implying not firmly known) area, "speculative" fits as it describes the prior lack of firm details. "Esoteric" means understood by few; "authoritative" means having authority (opposite as it was debated); "solitary" means alone (not relevant).

Answer:

D. speculative