What can be modified using the "self" keyword within a class?

The correct option indicates that instance variables specific to an instance can be modified using the "self" keyword within a class. In object-oriented programming, "self" refers to the instance of the class that is currently being created or accessed. When a method is called on an instance, "self" allows access to the instance’s attributes and methods.

When you define an instance variable within a class, you usually do so inside a method (commonly the constructor method) using the "self" keyword. For example, if you have self.variable_name, it creates or modifies an instance variable specific to that particular instance of the class. Each instance can have its own unique values for these instance variables, making them essential for maintaining state that is particular to each individual object created from the class.

In contrast, class methods and class variables are accessed in a different manner, typically using the class name itself, and global variables are not encapsulated within the class but exist at a broader scope. Therefore, the focus on "self" pertains directly to the instance variables, reinforcing their role in managing the unique data of each object within the class structure.