A mobile app for a library contains a 'Book' object with information about each book. If an app feature needs to display the title of a book, which aspect of the 'Book' object would the feature need to reference?
The feature would require a new variable outside the 'Book' object.
The feature would invoke a method of the 'Book' object.
The feature would need to reference a property of the 'Book' object.
The feature would construct a new class to extract the title information.