Based on Jalliah's research, which of the following explains the bed shortages during the COVID-19 pandemic in 2019-2021? Select all answers that apply a) Technology development is the reason for the hospital bed shortage. b) Economics of supply and demand are the reason for the bed shortage. c) The U.S. Population has increased by 53.1% from 1975-2020. d) Hospitals are certified by Medicare, Medicaid and Payers by the services they provide