The correct answer is: B. server
A server is a computer that is used to provide services to other computers. When you publish a message, a server is automatically created to store the message and deliver it to the intended recipients.
A client is a computer that requests services from a server. In the context of publishing a message, the client is the computer that is used to create the message and send it to the server.
A batch is a group of tasks that are executed together. In the context of publishing a message, a batch is not typically used.
A server is the correct answer because it is the computer that stores the message and delivers it to the intended recipients.