The correct answer is C. methods.
The client() class provides methods to create topics. A method is a function that is associated with a class. Methods are used to perform actions on objects. In the case of the client() class, the methods are used to create topics.
Option A is incorrect because software is not a method. Software is a general term for a collection of computer programs and data that are used to perform a specific task.
Option B is incorrect because classes are not methods. Classes are a way of organizing data and code into reusable units.
Option D is incorrect because batch is not a method. Batch is a way of processing data in large groups.