The Open Container Initiative (OCI) publishes open specifications for container images and container runtimes so that tools across the ecosystem remain interoperable. When a runtime is “OCI-compliant,” it means it implements the OCI Runtime Specification (how to run a container from a filesystem bundle and configuration) and/or works cleanly with OCI image formats through the usual layers (image → unpack → runtime). runC is the best-known, widely used reference implementation of the OCI runtime specification and is the low-level runtime underneath many higher-level systems. In Kubernetes, you typically interact with a higher-level container runtime (such as containerd or CRI-O) through the Container Runtime Interface (CRI). That higher-level runtime then uses a low-level OCI runtime to actually create Linux namespaces/cgroups, set up the container process, and start it. In many default installations, containerd delegates to runC for this low-level “create/start” work.

The other options are related but differ in what they are: Kata Containers uses lightweight VMs to provide stronger isolation while still presenting a container-like workflow; gVisor provides a user-space kernel for sandboxing containers; these can be used with Kubernetes via compatible integrations, but the canonical “native OCI runtime” answer in most curricula is runC. Finally, “runV” is not a common modern Kubernetes runtime choice in typical OCI discussions. So the most correct, standards-based answer here is A (runC) because it directly implements the OCI runtime spec and is commonly used as the default low-level runtime behind CRI implementations.

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