nswerWhich of these can not be used for a variable name in Java?Optionsidentifieridentifier & keywordkeywordnone of the mentioned

Break Down the Problem

1. Identify the options provided in the question.
2. Determine the rules for valid variable names in Java.

Relevant Concepts

1. Identifiers: In Java, an identifier is a name used to identify a variable, class, or function. Valid identifiers must start with a letter, underscore (_), or dollar sign ($) and can be followed by letters, digits, underscores, or dollar signs.
2. Keywords: Keywords are reserved words in Java that have a specific meaning in the language and thus cannot be used as variable names.

Analysis and Detail

1. Option 1: identifier - This is a general term and could refer to valid variable names.
2. Option 2: identifier & keyword - This combination suggests both a valid identifier and a keyword; therefore, it is incorrect as a variable name.
3. Option 3: keyword - Keywords cannot be used as variable names.
4. Option 4: none of the mentioned - This implies that all options can be used as variable names, which is false given that keywords can't be.

Verify and Summarize

From the analysis, we determine that keywords are the only items from the options given that cannot be used as variable names in Java.

Final Answer

The correct answer is keyword. Keywords cannot be used as variable names in Java.