Which of the following cannot be used as variables or functions in Python due to their specific meanings?

• A. Identifiers
• B. Keywords
• C. Operators
• D. Functions

Answer: (B)

In Python, keywords are reserved words that have a special meaning within the language itself. They are integral to the syntax and structure of the programming language and cannot be used as identifiers, such as variable names or function names. For example, words like "if," "else," "while," and "def" are keywords that denote specific constructs and behaviors in Python.

Since keywords are fundamental to the operation of the language, attempting to use them as variable or function names would lead to syntax errors or unintended behavior. Understanding this concept is key to effectively writing Python code, as it ensures that you do not inadvertently disrupt the language’s functionality.

Identifiers, on the other hand, are names that you define for variables, functions, classes, and other objects. Operators are symbols that perform operations on variables and values, such as arithmetic or logical operations. Functions, by definition, are blocks of reusable code identified by their names, which you can choose freely as long as they do not conflict with keywords or existing identifiers.