Final answer:
The drop in death rates and rise in life expectancy during the nineteenth century were due to improved sanitation, public health enhancements, and medical advancements, including vaccines and antibiotics.
Step-by-step explanation:
Nineteenth-century industrialization led to lower death rates and longer life spans primarily through advances in medical knowledge and technology. Factors such as improved sanitation, which included the development of cleaner water systems and better disposal of human waste, played a critical role in reducing the incidence of diseases. Public health improvements, like enhanced personal hygiene and public awareness about disease prevention, were also integral to the increase in life expectancy. Furthermore, medical advancements, including the development of immunizations for diseases such as diphtheria, cholera, and tuberculosis, and the discovery of antibiotics like penicillin, significantly brought infectious diseases under control. These innovations, combined with changes in the public's behavior regarding health, were largely responsible for the demographic shifts observed during the period, with an increase from an average life expectancy in the thirties in 1800 to one in the fifties by 1900