What does omitting "self" in an instance method affect?

Omitting "self" in an instance method impacts the ability to use instance variables because "self" acts as a reference to the instance of the class itself. When you define an instance method in Python, including "self" as the first parameter allows the method to access and modify the instance's attributes and other instance methods. Without "self," you cannot refer to instance variables, as they are scoped to the instance of the class, not the method itself.

In contrast, if "self" is omitted, the method would not have any context of which instance's variables it should be working with. This means that any reference to instance variables would lead to a NameError since Python would not recognize them as part of the method's local scope. Instance variables are tied to specific instances, and the inclusion of "self" is necessary to establish that connection.

The choices concerning only the method's return value, access to global variables, or suggesting that omitting "self" does not affect anything do not capture the fundamental role that "self" plays in instance methods and variable access.