When identifying Value Streams, SAFe recommends looking at how value flows to the customer. This typically means analyzing:
The internal departments which are supported (B): Understanding which departments contribute to the delivery of value helps map operational and development value streams.
The current products which the company sells (D): Products are often a clear indicator of value delivery.
Mapping products helps trace value from concept to customer.
Options A and C are not primary criteria for identifying value streams. Project cost accounting (A) is financial and administrative, and number of ARTs (C) is a result of value stream identification, not an input.
References:
SAFe 6.0 Website: Identify Value Streams and ARTs
SPC 6.0 Guide: "Look for existing products, solutions, and services delivered to the customer, and the people, systems, and steps involved in their flow of value."