How can you notify suppliers to register on the Ariba Network?

How can you notify suppliers to register on the Ariba Network?
A . Bulk upload the suppliers users through enablement workbook
B . Send an email to the supplier users via the message board
C . Generate password for supplier user in Ariba
D . Invite supplier users through sourcing event
E . Send invitations to the supplier users via SAP Ariba Discovery

Answer: A,C,D