Which of the Following Statements Is True About Direct Marketing

Which of the following statements is true about direct marketing?

A) Direct marketing refers to one-on-one interaction between a salesperson and a prospective buyer.
B) In direct marketing, the salesperson acts as an advisor who helps customers find the best solutions to their needs.
C) It is difficult to measure the results of direct marketing efforts.
D) Direct marketing is a static approach, with little scope for experimentation and improvement.
E) The heart of any direct marketing effort is a customer database.