Which document category combination is still mandatory?

With SAP S/4HANA embedded EWM OR EWM 9.5, you can skip certain document categories.

Which document category combination is still mandatory?
A . A production material request and a stock transfer
B . An outbound delivery request and an outbound delivery
C . An outbound delivery request and an outbound delivery order
D . An outbound delivery order and an outbound delivery

Answer: D