What is a contractual adjustment? 

a. An adjusting entry made at year-end to accrue unpaid patient service revenue. 

b. A reduction of patient service revenue for charity care. 

c. An allocation of the cost of patient care to the departments that supply the patient care. 

d. A reduction in patient service revenue because of agreements with third party payors that allow them to pay a health care entity based on the agreed upon determination of reasonable cost.