Which of the following income may enjoy a reduced tax or exclusion

A．direct advertising is the best way to promote a product
B．companies are trying to find the best way to sell their products
C．advertising is becoming enriched by the research in this area
D．old ways of advertising is giving ways to new ways of doing it

A．to send sample products from door to door
B．to familiarize the customers with the products
C．to deliver the products directly to the retail stores
D．to send information about the products in quick ways