The correct answer is: A. Objects
After defining a class, you can instantiate one or more objects. An object is an instance of a class. It is a concrete representation of a class. Objects have state and behavior. The state of an object is represented by its attributes. The behavior of an object is represented by its methods.
Option B is incorrect because a class is a blueprint for creating objects. It defines the attributes and methods that objects of that class will have.
Option C is incorrect because an attribute is a property of an object. It is a piece of data that describes the object.
Option D is incorrect because a method is a function that is associated with an object. It is a piece of code that performs an action on the object.