Which of the following is a valid identifier in Python?

Correct option is C

In Python, a valid identifier is a name used to identify a variable, function, or other object. The identifier variable_name is valid because it follows all Python naming conventions:
· It begins with a letter or underscore (_).
· It only contains letters, digits, or underscores.
· It does not use any reserved keywords (like for, if, etc.).
· It does not contain special characters like @, -, or spaces.
Important Key Points:
1. Python identifiers:
· Must begin with a letter (A-Z, a-z) or an underscore _.
· Can contain alphanumeric characters and underscores (A-Z, a-z, 0-9, _).
· Are case-sensitive (variable and Variable are different).
· Cannot be Python keywords or contain special characters like - or @.
2. Examples of valid identifiers:
· _variable
· variable_name
· var123
3. Examples of invalid identifiers:
· 1stVariable (starts with a digit).
· variable-name (contains a hyphen).
· variable@name (contains @).
· for (reserved keyword).
Knowledge Booster:
· 1stVariable: Invalid because it starts with a digit, which is not allowed in Python identifiers.
· variable-name: Invalid because it contains a hyphen (-), which is not a permitted character.
· for: Invalid because it is a reserved keyword in Python. Reserved keywords cannot be used as identifiers.
· variable@name: Invalid because it contains the special character @, which is not allowed in identifiers.