How does NetSuite set up a company record when you buy from and sell to the same company?

How does NetSuite set up a company record when you buy from and sell to the same company?
A . either the vendor or the customer can be set as "Parent of" the other record to link them
B . NetSuite tracks this using the "Other relationship" functions to link the customer and vendor records
C . NetSuite uses a single company record to track this combined relationship
D . NetSuite uses unrelated customer and vendor records to track these

Answer: B