Which of the following can be used as valid variable identifier(s) in Python?

The correct answer is Option 3 (total).

Key Points

• In Python, variable identifiers must begin with a letter (A-Z or a-z) or an underscore (_) and can be followed by letters, digits (0-9), or underscores.
• The identifier total is valid because it follows Python's naming conventions and does not conflict with reserved keywords.
• Reserved keywords such as global cannot be used as variable names in Python as they have predefined meanings in the programming language.
• Other valid identifiers from the options include question and salute, but they are not the correct answer as per the provided question context.
• Python is case-sensitive, meaning that identifiers like Total (with an uppercase 'T') would be treated differently from total.

Additional Information

• Reserved Keywords in Python
  • Python has 35 reserved keywords as of Python 3.10, including global, def, return, class, if, else, etc.
  • These keywords are case-sensitive and cannot be used as identifiers.
• Rules for Variable Naming in Python
  • Variable names can include letters, numbers, and underscores but must not begin with a digit.
  • Special characters such as @, $, %, etc., are not allowed in variable names.
  • Variable names should not conflict with reserved keywords.
• Case Sensitivity in Python
  • Python is case-sensitive, meaning myVariable and MyVariable would be considered different identifiers.
• Best Practices for Variable Naming
  • Use meaningful and descriptive names, such as total_price or user_age, to improve code readability.
  • Follow snake_case (e.g., my_variable) for variable names as per Python's PEP 8 guidelines.