Where do you define the discount agreement within a master agreement?

Where do you define the discount agreement within a master agreement?
A . SAP S/HANA Service: SOM and SAP S/4HANA Convergent Invoicing
B. SAP S/HANA Service: SOM, SAP S/HANA Convergent Invoicing, and SAP Convergent Charging
C. Only SAP S/HANA Service: SOM
D. Only SAP S/HANA Convergent Invoicing

Answer: D