What functionality does the Pay as you Grow licensing on the Cisco ASR 901 provide?

A.
the ability to only pay for the resources (memory, processor, storage) that you need and
as you use more, your cost increases

B.
the ability to add bandwidth dynamically to a link

C.
the ability to increase the number of devices at a cell site without additional configuration

D.
the ability to license additional ports as your needs increases