Final answer:
Technological advancements in clean water and sanitation systems, changes in public behavior, and advancements in medicine have contributed to the increase in life expectancy.
Step-by-step explanation:
The rise in life expectancy can be attributed to three primary factors: clean water and sanitation systems, changes in public behavior, and advancements in medicine. Clean water and sanitation systems help prevent the transmission of diseases. Changes in public behavior, such as practicing good hygiene and reducing tobacco use, have improved overall health. Additionally, advancements in medicine, including immunizations and antibiotic drugs, have played a significant role in extending lives.