Token in C language

A token in programming languages is the smallest unit of meaning or a lexeme that the compiler recognizes. In the C language, tokens can be classified into several categories, including keywords, identifiers, constants, string literals, operators, and punctuators.

Explanation:

Keywords:
Keywords in C language are reserved words that have predefined meanings and cannot be used as identifiers. Some examples of keywords in C are `if`, `else`, `for`, `while`, `int`, `float`, `void`, etc. Keywords are used to define the syntax and structure of the language.

Identifiers:
Identifiers are names given to variables, functions, or any other user-defined entities in a program. These names are used to refer to the entities in the program. An identifier can consist of letters, digits, and underscores, but it must start with a letter or an underscore. Examples of identifiers in C are `count`, `sum`, `average`, etc.

Constants:
Constants are fixed values that do not change during the execution of a program. There are different types of constants in C, including integer constants, floating-point constants, character constants, and string literals. Examples of constants in C are `10`, `3.14`, `'A'`, `"Hello"`, etc.

Operators and Punctuators:
Operators are symbols that perform mathematical or logical operations on operands. Examples of operators in C are `+`, `-`, `*`, `/`, `%`, `==`, `!=`, `&&`, `||`, etc.

Punctuators are symbols used for punctuations and grouping in C programs. Examples of punctuators in C are `,`, `;`, `()`, `{}`, `[]`, etc.

Whitespace:
Whitespace refers to spaces, tabs, and newlines in a program. It is used to separate tokens and improve the readability of the code. Whitespace is not considered a token in C language as it does not have any meaning or significance in the program execution.

Conclusion:
In the given options, the correct answer is option 'D' - Whitespace. Whitespace is not considered a token in the C language. Tokens in C include keywords, identifiers, constants, operators, and punctuators, but whitespace is not considered a token as it does not have any meaning or significance in the program execution.