Esparta e Atenas têm inúmeras diferenças de origens culturais, econômicas, geográficas e sociais. Enquanto Atenas é mencionada por ter sido a pátria de grandes pensadores e filósofos, Esparta é conhecida historicamente por sua rígida formação militar que objetivava preparar soldados quase invencíveis que rejeitavam qualquer tipo de fraqueza. Contudo, Esparta e Atenas têm como característica comum

The correct answer is B) the fact that they were poleis (cities) of Greece.

To understand why this is the correct answer, let's analyze the characteristics of both Sparta and Athens. Both cities were part of ancient Greece, and as such, they shared a common cultural, economic, geographic, and social background. However, they also had significant differences that set them apart. Athens was known for being the cradle of great thinkers and philosophers, whereas Sparta was famous for its rigid military formation, which aimed to prepare almost invincible soldiers who rejected any type of weakness.

Despite these differences, one common characteristic that unites both cities is the fact that they were poleis, or city-states, of ancient Greece. This means that they were independent cities with their own governments, economies, and cultures, but still shared a common Greek identity.

The other options do not accurately describe a common characteristic shared by both Sparta and Athens. Option A, the form of government, is incorrect because Sparta had an oligarchic government, whereas Athens had a democratic government. Option C, the defense of democracy, is also incorrect because, although Athens was a democracy, Sparta's government was not. Option D, the rejection of tyranny, is also incorrect because, while both cities rejected tyranny, this was not a unique characteristic that united them.

Therefore, the correct answer is option B, the fact that they were poleis of Greece, which accurately describes a common characteristic shared by both Sparta and Athens.