In the Linux/Unix environment normally assumed for OCI container development, the Docker client communicates with the locally running Docker daemon through a UNIX domain socket. Docker ' s default endpoint on Linux is unix:///var/run/docker.sock. This allows local inter-process communication without requiring a TCP network connection. TCP can be configured when the client must communicate with a daemon through a network, while SSH can provide secure access to a remote Docker daemon. RPC is not the default Docker client transport. Therefore, for a Docker client and daemon running locally on a Linux-based OCI development host, Local UNIX Sockets is the correct answer. On Windows, Docker uses a named pipe by default, so the answer is specifically applicable to the Linux/Unix OCI context.