The reduce() method in JavaScript is used to apply a function to an accumulator and each element of the array (from left to right) to reduce it to a single value. It's often used for tasks like summing up values or aggregating data. The correct option is reduce.

To declare a string variable in JavaScript, you use the var keyword followed by the variable name (text) and assign the value (Hello World) using the equal sign (=). The correct syntax is var text = "Hello World";. Variables are case-sensitive in JavaScript, so make sure the variable name matches the case.

Object.create(null) is used when you need an object with no prototype chain (a "null prototype"), which means it won't inherit any properties or methods from Object.prototype. This can be useful for creating objects where you want complete control over the properties and avoid unintentional inheritance.

In JavaScript, you can create an object using the Object.create() method. This method allows you to specify the prototype object from which the new object should inherit properties and methods. The new Object() syntax is less commonly used for object creation.

AJAX stands for "Asynchronous JavaScript and XML." It is a set of web development techniques used to create asynchronous web applications. While XML was commonly used in the past, JSON is more prevalent today for data interchange in AJAX requests.

You can add a new property to a JavaScript object by simply assigning a value to a new property name. For example, myObject.newProperty = 'some value';. While you can use methods like Object.assign() to copy properties from one object to another, it's not used for adding new properties. There's no Object.addProperty() or addProperty() method.

A Module is a self-contained block of code in JavaScript that manipulates data and can be thought of as an object in object-oriented programming. Modules help encapsulate functionality and data, providing a clean and organized code structure.

In JavaScript, the prototype property is a reference to an object from which the current object inherits properties and methods. When you access a property or method on an object, JavaScript first looks for it on the object itself and then, if not found, on its prototype. Understanding prototypal inheritance is crucial in JavaScript.

The pop() method in JavaScript removes the last element from an array and returns that removed element. It's useful when you need to remove and capture the last item in an array. For instance, let removed = myArray.pop() would remove the last element from myArray and store it in the removed variable.

In JavaScript, NaN is not equal to itself. So, the expression NaN == NaN evaluates to false. This behavior is because NaN represents a value that is "Not-a-Number," and it's treated as unordered and not equal to any other value, including itself.