Why was cream skimming popular among the sickness insurance funds in Germany before the payment reforms in 2009? a) Capitation payments to sickness funds were uniform across the population. b) Capitation payments to sickness funds had inadequate risk adjustment by age and sex only. c) Capitation payments to sickness funds were too complicated and unbalanced, requiring categorization into one of 152 risk groups. d) Payments to sickness funds were based on a fee-for-service system. e) The most profitable patients used to be the sickest patients, as Morbi-RSA set some of its morbidity-adjusted payments too high.