Which command is used to configure the VTP password on a switch?

To configure the VTP (VLAN Trunking Protocol) password on a switch, the correct command is indeed "vtp password password." This command allows network administrators to secure the VTP domain by requiring a password for switches to send VTP advertisements.

When VTP is configured with a password, only switches that have the correct password will participate in the VTP domain, thereby preventing unauthorized devices from affecting the VLAN configuration across the network. This is crucial for maintaining the integrity of VLAN information and ensuring that only trusted devices can influence VLAN propagation.

The other options provided do not reflect the correct syntax or command structure used in Cisco IOS. They do not accurately represent the method to establish a VTP password, which must follow the required command format that is specifically designed for configuring the VTP password.