What Are Two Functions of a Network Services Orchestrator in an NFV

Multiple Choice

What are two functions of a Network Services Orchestrator in an NFV environment? (Choose two.)

A) It operates at the resource-facing services layer and provides overall lifecycle management at the network service level.
B) It provides an API-based northbound interface for transparent integration with systems that operate at the resource-facing services layer.
C) It provides a standards-based southbound interface for transparent integration with systems that operate at the customer-facing services layer.
D) It provides a standards-based northbound interface for transparent integration with systems that operate at the customer-facing services layer.
E) It operates at the customer-facing services layer and provides the management interface for the virtual network devices.