Final answer:
The GBD Human Resources for Health Study indicates a significant impending shortage of healthcare workers. Although the exact figure is not provided in the referenced material, the demand for geriatric care specialists alone is expected to require over 33,000 professionals by 2025.
Step-by-step explanation:
According to the GBD Human Resources for Health Study, there is a projected need for a significant number of healthcare workers. Due to the growing numbers of seniors, as a result of shifting demographic age pyramids, and expansion of healthcare access, the demand for healthcare professionals is increasing. The provided information does not specify the exact number from the options given (A) 50.4 million, (B) 50.3 million, (C) 43.0 million, or (D) 40.3 million. However, the demand for geriatric specialists is expected to surge by 45% by 2025, requiring over 33,000 such specialists to meet healthcare needs, especially considering there were only 6,320 geriatrics specialists in the United States as of 2020.