The correct answer is B. publish().
The publish() method is used to publish messages to a pub/sub topic. It takes two arguments: the topic name and the message data. The topic name is a string that identifies the topic to which the message will be published. The message data is a string that contains the message to be published.
The client() method is used to create a client object. The server() method is used to create a server object. The batch() method is used to batch messages together before publishing them.
Here is an example of how to use the publish() method:
“`
import pubsub
topic = “my_topic”
message = “Hello, world!”
publisher = pubsub.Publisher()
publisher.publish(topic, message)
“`
This code will publish the message “Hello, world!” to the topic “my_topic”.