In Python, identifiers are names for variables, functions, classes, modules, or objects.
Identifiers cannot be reserved or built-in keywords.
Options (A) global, (C) def, and (D) with are Python keywords and thus invalid as identifiers.
Option (B) Break begins with an uppercase 'B', differentiating it from the lowercase keyword break.
As Python is case-sensitive, Break is not a keyword and is therefore a valid identifier.
Consequently, option (B) is the correct choice.