Select the most appropriate set of words from the given choices to fill in the blanks.

As navigators, calendar makers, and other _________ of the night sky accumulated evidence to the contrary, ancient astronomers were forced to __________ that certain bodies might move in circles about points, which in turn moved in circles about the earth.

A. scrutinizers, believe

B. observers, agree

C. scrutinizers, suggest

D. observers, concede

Please do not use chat terms. Example: avoid using "grt" instead of "great".