Scientists must be impartial and not base their conclusions on a. opinions b. models c. evidence d. experiments

Scientists must be impartial and not base their conclusions on A. Opinions.

Scientists should not base their conclusion of a certain topic or discussion depending on the opinion of other people. As a scientist, someone should based the conclusions on the facts and data gathered through experimentation, models, and evidences. Thus, the answer is A. 

The answer is b hope this