One of the Advantages of Personal Selling as Compared to Advertising

One of the advantages of personal selling as compared to advertising is that:

A) salespeople can be so closely supervised.
B) salespeople can become very persuasive since they give an identical sales presentation to so many different people.
C) salespeople can rely on puffery.
D) salespeople can change their message if they find their customers losing interest.
E) all of the above.