Answer: B. Polluted air and drinking water
Step-by-step explanation:
The rapid growth of 19th-century cities led to significant problems, but the greatest health risk was the pollution of air and drinking water. Industrialization and urbanization brought about overcrowding, inadequate sanitation, and increased pollution. Cities often lacked proper sewage systems and waste management, resulting in the contamination of drinking water sources and the release of pollutants into the air. This pollution contributed to the spread of diseases such as cholera and typhoid, which posed significant health risks to the urban population.