Transcription: If you compare this definition of the PhoneBook class with the definition in earlier chapters, you will see that they are very similar. The interface to the client code is unchanged, but the class now has only one data member, a list object. The member functions have been altered to use the list, ListIter, and PhoneNum classes. A PhoneBook object is now implemented as a linked list, and the items in the list are linked in alphabetical order by the name field.