Final answer:
California, Texas, and New York have the most total professionally active physicians due to their large populations and extensive healthcare systems.
Step-by-step explanation:
The states of a) California, Texas, and New York have the most total professionally active physicians in the US. Sizeable populations in states like California and Texas, as well as New York being a densely populated area and a significant hub for healthcare and research, contribute to a greater demand for healthcare professionals and, thus, a higher number of active physicians.
It's important to note that while three states, California, Texas, and Florida, account for a large portion of the US population growth, the question specifically asks about the number of active physicians. Thus, the correct option for the states with the most total professionally active physicians in the US would be a) California, Texas, New York. This aligns with the sheer size and population of these states, and the extensive healthcare systems required to support their populous cities.