How do health maintenance organizations (hmos) and preferred provider organizations (ppos) differ? a. hmos provide health insurance for older adults; ppos provide insurance for children. b. hmos will be eliminated because of the affordable care act (aca); ppos will not. c. hmos provide preventative health care options within a network of preapproved providers; ppos have agreements with providers to provide care at a reduced amount. d. hmos are considered to be better than ppos.