Final answer:
In Cisco ACI's spine and leaf model, each leaf device connects to all spine devices to facilitate high-bandwidth, low-latency communications across the data center.
Step-by-step explanation:
The spine and leaf model within Cisco's Application Centric Infrastructure (ACI) employs a specific connectivity approach. In this model, each leaf device connects to each spine device. This creates a network topology where every leaf switch is interconnected with every spine switch, allowing for high-bandwidth, low-latency communication paths across the data center network. It is important to note that the options where each spine device connects to every other device and each leaf device must connect to each other leaf device do not accurately describe the spine and leaf network topology. Instead, the leaf switches connect all end devices, like servers and storage, while spine switches act as a backbone, interconnecting all the leaf switches.