Which of the following options is a correctly formatted variable name in most programming languages?

Correct option is C

abc_123 is a correctly formatted variable name in most programming languages. It follows common naming rules, such as starting with a letter and using an underscore, which is generally allowed.
Important Key Points:
1. Variable names in most programming languages must start with a letter or an underscore.
2. Underscores (_) are often allowed in variable names to improve readability.
3. Numbers can be used in variable names, but they cannot be at the beginning.
Knowledge Booster:
· 123abc: This is not allowed as a variable name because it starts with a number, which violates most naming rules.
· abc!123: The character ! is not allowed in variable names in most languages because it is a special symbol often used for logical operations.
· abc-123: The character - is not permitted in variable names since it is interpreted as the subtraction operator in programming.
· abc 123: Spaces are not allowed in variable names, as they create ambiguity. Instead, underscores (_) are commonly used for separation in variable names.