Q.Which of the following is the correct identifier? (A) global (B) Break (C) def (D) with

Concept: Valid identifiers in Python — an identifier must start with a letter or underscore, followed by letters, digits, or underscores, and cannot be a reserved keyword.

Step 1: Check each option against Python's reserved keywords.

• global is a keyword → invalid.
• Break starts with a capital letter, and Python keywords are case-sensitive; break is a keyword, but Break is not → valid. …

The Concept: What Makes a Valid Identifier in Python?

In Python, an identifier is simply a name you give to a variable, function, class, or other object. The rules are strict:

• It must start with a letter (a–z, A–Z) or an underscore (_).
• The rest can be letters, digits (0–9), or underscores.
• It cannot be a reserved keyword (like if, for, def, global, etc.).
• Python is case-sensitive, so Break and break are different names.

The trick here is that the options mix keywords and non-keywords, and case-sensitivity is the deciding factor. Let's check each one.

Step-by-Step Reasoning

1. Option (A): global

   global is a Python keyword used to declare a variable as global inside a function. Since it's a reserved word, it cannot be used as an identifier. So this is invalid.

2. Option (B): Break

   Python has a keyword break (all lowercase) used to exit loops. But Break with a capital B is a different string. Python is case-sensitive, so Break is not a keyword — it's a perfectly valid identifier. You could name a variable Break if you wanted (though it's not recommended for readability). This is the correct choice.

3. Option (C): def …