According to the passage, a designer of products is pre occupied with the following problems EXCEPT ______.

A．people are more concerned with tile image of a product rather than the product itself
B．it saves manufacturers from considering how the products can appeal to customers
C．there are all kinds of media available
D．there are many excellent advertisers who can make their voices authoritative

A．providing students with help when necessary
B．finding out students' mistakes and correcting them
C．teaching students the essential knowledge that they will need in their future life
D．telling students the correct answers