The correct answer is: A. r user-list
The r command is used to forward mail to a user or group of users. The syntax is r user-list, where user-list is a list of users or groups separated by commas. For example, to forward all mail to the user johndoe, you would use the command r johndoe.
The m command is used to mail a message to a user or group of users. The syntax is m user-list, where user-list is a list of users or groups separated by commas. For example, to mail a message to the user johndoe, you would use the command m johndoe.
The d command is used to delete a message. The syntax is d message-id, where message-id is the unique identifier of the message. For example, to delete the message with the message ID 1234567890, you would use the command d 1234567890.
The e command is used to edit a message. The syntax is e message-id, where message-id is the unique identifier of the message. For example, to edit the message with the message ID 1234567890, you would use the command e 1234567890.