Which of the following provides secure, private communication between cloud environments without provisioning additional hardware...

VPC peering provides secure, private communication between cloud environments without the need for provisioning additional hardware or appliances. It allows direct network connectivity between two Virtual Private Clouds (VPCs), enabling resources in either VPC to communicate with each other using private IP addresses.

Cloud networking options such as VPC peering and its benefits are included in the networking concepts of cloud environments in the CompTIA Cloud+ certification.