正解:C
To test connectivity from the guest shell of the NX-OS, the command that should be used is ping vrf management [IP address]. This command sends ICMP Echo requests to the specified IP address within the management VRF, which is useful for verifying network connectivity from the guest shell environment.
References := For more detailed procedures and explanations, one would refer to the Cisco Data Center Core Technologies (DCCOR) study materials, which provide in-depth knowledge on managing and operating Cisco Nexus switches and their features, including the use of the guest shell for network connectivity tests.