Based on this information, the difference between Millar's description and Polybius' description is the fact that Millar is a modern scholar and based on his description, he is more likely to be objective in his assessment of the Roman Empire. Polybius is an ancient scholar, and a great admirer of the Roman empire. These two qualities suggest that he might be less objective when analyzing the history of the empire.
People flocked to the cities in the late 1800's because during this time factories were booming and there was more opportunity in the cities. Therefore the answer is B.
