What is a reserved word in programming?

A reserved word in programming refers to a word that is used by the programming language for a specific purpose, which is why option B is the correct choice. These words are part of the syntax and structure of the language, and they typically represent commands, control structures, data types, or similar constructs that the language recognizes and processes in a defined way.

Because they have special meanings, reserved words cannot be used as identifiers for variables, functions, or any user-defined entities within the code, which helps prevent conflicts and ensures that the language can interpret the code correctly. For example, in languages like Python or Java, keywords such as "if," "else," "while," and "class" are reserved words that perform specific functions that are integral to the execution of programs.

The other options do not correctly define what a reserved word is. A word that has no special meaning in a language would not be a reserved word at all and could potentially be used freely. The notion of a type of variable that cannot be changed relates to constants rather than reserved words. Lastly, a command that is optional in programming syntax refers to statements or keywords that may be included at the programmer's discretion, which again is separate from the concept of reserved words that must be