To meet the requirements specified, two actions must be taken: B. Create a standard contract between EPG 51 and EPG 10 to explicitly allow communication between these two EPGs. A contract in Cisco ACI defines the communication policy between EPGs, and by creating a standard contract, specific communication can be permitted. E. Enable the Preferred Group option on EPGs 1 to 50 to allow communication within this group of EPGs. The Preferred Group feature in ACI allows all EPGs within the group to communicate with each other without the need for explicit contracts, while still enforcing contracts for communication with EPGs outside the group. References := Implementing Cisco Application Centric Infrastructure Official Cert Guide