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.

Correct Answer : D.

Students would be a very casual option for the first blank. So we have to choose among scrutinizers and observers. However, the second part of the sentence describes how the ancient astronomers were forced to change their opinion in the
Fill in the Blanks (FIB) l 243
face of contradictory evidence. When someone is compelled to accept defeat, 'concede' is the best word that can be used.