Final answer:
The development of employer-sponsored health insurance in the United States was influenced by precedents set by other countries and the Affordable Care Act (ACA).
Step-by-step explanation:
The impetus for the development of employer-sponsored health insurance in the United States can be attributed to a variety of factors. In the early 20th century, countries like Germany, France, Britain, and Russia implemented laws that required employers to provide health insurance for their employees. These laws served as precedents and influenced the development of employer-sponsored health insurance in the U.S. as well. The Affordable Care Act (ACA) also played a significant role in the mandate for employer-sponsored health insurance.