America Was on Its Way to Creating a Holistic Health-Care

America was on its way to creating a holistic health-care system until which of the following events marked the beginning of a change of focus for health care?

A) Discovery of sulfa in the 1930s
B) Introduction of health-care insurance in the 1940s
C) Immigration of Europeans in the 1920s
D) Rural to urban migration of people in the 1950s