Access modifiers are essential components in object-oriented programming that determine the visibility and accessibility of classes, methods, and variables within different contexts of a program. By employing access modifiers, a programmer can enforce encapsulation, which is a core principle of object-oriented design.
When using access modifiers, you can specify who can access certain parts of your class. For instance, a method marked as "private" can only be accessed within the class it is defined, while a "public" method can be accessed from outside the class. This helps in controlling how the data and functionalities can be accessed and modified, contributing to a more robust and secure codebase.
While performance optimization, global variable declarations, and response times are important concepts in programming, they do not pertain directly to the definition or functionality of access modifiers. Thus, the answer highlighting access modifiers as keywords that set the accessibility of classes and methods accurately captures their role and significance in object-oriented programming.