When Rohit opened the door on hearing the doorbell, there was a salesman who sold Encyclopaedia Britannica. He was also offering- that on buying one 'World Encyclopaedia'. you will get 'Animal Encyclopaedia' free. Britannica is using which element of promotion mix in this example?
Personal Selling
Personal Selling involves the oral presentation of messages in the form of conversation with one or more prospective customers for the purpose of making sales.