Explanations:The concept of sanitation in ancient cities is closely tied to the development of urban infrastructure, particularly drainage systems. In many ancient civilizations, including those in India, the construction of complex drainage systems was a critical aspect of urban planning. These systems were designed to manage waste and water, thereby reducing the risk of waterborne diseases and maintaining a cleaner environment.
Drainage systems in ancient cities were often sophisticated, with networks of channels and sewers that carried waste away from residential and commercial areas. In some cases, these systems were even covered to prevent contamination and to manage the flow of waste more effectively. The presence of such systems indicates a high level of urban planning and a concern for public health, which was essential for the well-being of the city's inhabitants.
While other factors such as military presence, political leadership, and economic activity were important for the functioning of a city, they did not directly contribute to its sanitation. Soldiers were primarily responsible for security and defense, and the presence of emperors or political leaders did not ensure cleanliness without the necessary infrastructure. Similarly, large markets were important for trade and commerce but could contribute to unsanitary conditions if not managed properly.
Therefore, the correct answer is that the cities were sanitary because they had complex drainage systems. This infrastructure was crucial for maintaining cleanliness and preventing the spread of diseases, which were significant concerns in ancient urban environments.