The literal 'use strict' inside myFunction activates strict mode only for that function’s body (ECMAScript allows function-level strictness).

Outside the function, code executes in non-strict (sloppy) mode.

• Line 08 assigns z = x (3.14) successfully, so z == 3.14 (B).

• Strict mode applies to every statement inside myFunction (lines 05 only), not to outer code—thus it “has effect only on line 05” (D).

• Inside strict code, assigning to an undeclared identifier (y = x) throws a ReferenceError (E).

A. Directive is not global; it does not affect lines before/after the function.

C. Scope is limited to the function, not the entire file after line 04.

1. ECMAScript 2021 §12.1.1 “Directive Prologues and Strict Mode” – strict mode can be function-local.

2. ECMAScript 2021 §15.1.1.1 – in strict mode, assignment to an undeclared variable throws ReferenceError.

3. Stanford CS142 lecture notes, “JavaScript Strict Mode,” Slide 6 – emphasises function-level granularity and resulting errors.