Which of the following is the best title for the passage

A．lack of the capacity to handle calls on wireless systems due to the greatly increasing phone users
B．the plunge in prices for wireless service
C．lack of call centers to deal with the customers' complaints
D．the technical complexity of sending and receiving wireless calls

A．to ban publications and cut films
B．to ensure there is no dirty content in books, plays or films
C．to distinguish works of art from others
D．to place the entertainment industry under his control