Comparing the Inpatient Prospective Payment System (IPPS), Medicare Severity Diagnosis-Related Groups (MS-DRGs), and the AllPatient-Refined Diagnosis-Related Groups (APR-DRG) system, which feature app"

a. Patient classification based on diagnosis, severity, and resource utilization.
b. Hospital reimbursement methodology for Medicare patients.
c. Tools used to categorize patients into groups for billing and payment purposes.
d. All of the above.