Final answer:
The 'enable password' command is used to configure a previously encrypted password to access enable mode on a Cisco device. It sets a password for the privileged exec mode but does not encrypt it; 'enable secret' should be used for encryption.
Step-by-step explanation:
The option that configures a previously encrypted password for gaining access to enable mode is d) enable password. When configuring a Cisco router or switch, administrators can use the enable password command to set a password that will be required to transition from user exec mode to privileged exec mode. However, if the password has already been encrypted using the service password-encryption command, setting or changing the enable password will not affect the encryption of the password; it will only define the password. To ensure the password is encrypted in the device's configuration file, the enable secret command should be used instead, since it automatically uses a stronger encryption algorithm.