In Hyper-V, which type of switch settings allows communication between virtual machines on the same host while not allowing communication with an external network?

The correct answer is C. Private.

In Hyper-V, a Private virtual switch allows communication only between virtual machines that are connected to it on the same host. It prohibits any communication with the external network or the host itself, effectively isolating the VMs from everything outside of their group. This setup is useful for scenarios requiring secure communication between VMs without outside interference.