Which configuration steps will accomplish this task?

You are required to implement a Contrail service that will automatically increase network resources for that service when under high traffic loads, and reduce network resources for that service under low traffic loads.

Which configuration steps will accomplish this task?
A . Configure Heat to monitor the CPU threshold of services VMs, and configure a Heat auto-scaling policy to adjust the VM resources allocated to the service.
B . Configure Ceilometer to monitor the CPU threshold of services VMs, and configure a Ceilometer auto-scaling policy to adjust the VM resources allocated to the service.
C . Configure Heat to monitor the CPU threshold of services VMs, and configure a Ceilometer auto-scaling policy to adjust the VM resources based on alarms generated by Heat.
D . Configure Ceilometer to monitor the CPU threshold of services VMs, and configure a Heat auto-scaling policy to adjust VM resources based on the alarms generated by Ceilometer

Answer: D