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The verified answer is A .

This constructor function runs when new Person() is called:

function Person() {

this.firstName = " John " ;

}

So this line:

const myFather = new Person();

creates an object like this:

{

firstName: " John "

}

Then the prototype is assigned a method named job:

Person.prototype = {

job: x = > " Developer "

};

Because myFather is created from Person, it can access properties and methods from Person.prototype.

So:

myFather.firstName

returns:

" John "

And:

myFather.job()

returns:

" Developer "

Therefore:

const result = myFather.firstName + " " + myFather.job();

becomes:

const result = " John " + " " + " Developer " ;

Final value:

" John Developer "

Option B is incorrect because job() returns " Developer " , not undefined.

Option C is incorrect because job exists on Person.prototype, so it is callable.

Option D is incorrect because firstName is assigned inside the constructor.

Therefore, the verified answer is A .

New behavior: sum3 now returns the sum of all elements .

Line 01: sum3([1, 2, 3]) → 1 + 2 + 3 = 6

Assertion on line 02: res === 6 → passes.

Line 04: sum3([1, 2, 3, 4]) → 1 + 2 + 3 + 4 = 10

Assertion on line 05: res === 6 → 10 === 6 is false, so the assertion fails.

So:

Line 02 assertion passes → D.

Line 05 assertion fails → C.

import * as lib from ' ... ' imports all named exports from the module into the namespace object lib.

You then call:

lib.foo();

lib.bar();

Option D correctly imports only foo and bar, not every function. The question explicitly says “import every function… and then call foo and bar”, so A best matches.

Options B and C are invalid syntax or reference the wrong identifier.

JSON.stringify() applies the following rules:

String objects (new String( ' false ' )) Are converted to their primitive string values . So:

new String( " false " ) → " false "

Boolean objects (new Boolean(false)) Convert to their primitive boolean value :

new Boolean(false) → false

Undefined values inside arrays According to the JSON specification, undefined becomes null when stringifying an array:

JSON.stringify([undefined]) → " [null] "

Therefore, the array becomes:

[ " false " , false, null]

And JSON.stringify wraps it in quotes:

' [ " false " , false, null] '

This is exactly option A.

JavaScript Knowledge References (text-only)

Object wrappers (String, Boolean) are converted to primitives during JSON serialization.

undefined becomes null inside arrays when stringified.

JSON.stringify() follows the JSON data-model rules strictly.

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