In the C plus plus programming language, which of the following options correctly describes the status of identifiers, keywords, and string literals as tokens of the language?

Introduction / Context:
When a C plus plus program is compiled, the compiler performs lexical analysis and breaks the source code into tokens. Tokens are the smallest meaningful units such as identifiers, keywords, literals, operators, and punctuation. Understanding what counts as a token is a core part of language fundamentals and is commonly tested in multiple choice questions.

Given Data / Assumptions:

• The language is standard C plus plus.
• The options refer to identifiers, keywords, and string literals.
• We want to know which of these are treated as tokens by the compiler.

Concept / Approach:
During lexical analysis, the compiler scans the source code and groups characters into tokens that the parser can handle. Identifiers, such as variable and function names, are tokens. Keywords, such as if, while, class, and return, are also tokens. String literals like "Hello" are treated as literal tokens. Since all three belong to the set of tokens recognised by the C plus plus compiler, the correct statement must list all of them as tokens.

Step-by-Step Solution:
Step 1: Remember that identifiers are names given to variables, functions, classes, and other entities in C plus plus. Step 2: Recall that keywords are reserved words with special meaning, such as for, if, else, switch, and class. Step 3: Understand that a string literal like "text" is treated as a literal token by the lexical analyser. Step 4: Recognise that each of these categories is a token type used in the grammar of the language. Step 5: Choose the option that states that identifiers, keywords, and string literals are all tokens.

Verification / Alternative check:
You can verify this by looking at a simple line of code such as string message = "Hi";. The compiler sees tokens like string, message, equals sign, the string literal, and the semicolon. This demonstrates that both the identifier message and the string literal "Hi" are tokens, along with the keyword string or the type name, depending on the context.

Why Other Options Are Wrong:
Option A: Claims that only identifiers are tokens and excludes keywords and string literals, which contradicts the behaviour of real compilers. Option B: Limits tokens to keywords and excludes identifiers and string literals, which again is not correct. Option D: States that none of the listed categories describe valid tokens, which is clearly false because all three are fundamental token types.

Common Pitfalls:
Students sometimes confuse the concept of tokens with the concept of data types or language constructs. Another mistake is to think that only operators and punctuation are tokens. Remember that tokens include many categories: identifiers, keywords, literals, operators, and separators. Recognising these categories helps you understand how the compiler reads your code and why certain syntax errors occur.

Final Answer:
In C plus plus, Identifiers, keywords, and string literals are all recognised as tokens in C plus plus.