For which of the following business objects can you create invoice schedules in SAP Business...

You can create invoice schedules in SAP Business ByDesign for both contracts and sales orders. With invoice schedules, you can define the billing frequency, billing date, and other parameters for billing your customers. For example, you can define a frequency of "monthly" and the associated billing date to generate invoices for your customers on a monthly basis. Reference: https://help.sap.com/viewer/5e5e864b7f16425e9f36e7f74ce671d2/1911/en-US/d7b8c23f6d724fecac1c7d8aca9f2f7e.html