单选题：根据下面资料，回答题 The Language of Music A painter hangs his or her

根据下面资料，回答题
The Language of Music
A painter hangs his or her finished picture on a wall, and everyone can see it. A composer writesa work,but no one can hear it until it is performed. Professional singers and players have great responsibilities, for the composer is utterly dependent on them. A student of music needs as long and as
arduous a training to become a performer as a medical student needs to become a doctor. Mosttraining is concerned with technique ,for musicians have to have the muscular proficiency of an athlete or a ballet dancer. Singers practice breathing every day, as their vocal chords would be inadequate without controlled muscular support. String players practice moving the fingers of the left handup and down, while drawing the bow to and fro with the right arm--two entirely different movements.
Singers and instrumentalists have to be able to get every note perfectly in tune. Pianists arespared this particular anxiety, for the notes are already there, waiting for them, and it is the pianotuner' s responsibility to tune the instrument for them. But they have their own difficulties:thehammers that hit the strings have to be coaxed not to sound like percussion (撞击、碰撞) and eachoverlapping tone has to sound clear.
This problem of getting clear texture is one that confronts student conductors : they have to learnto know every note of the music and how it should sound, and they have to aim at controlling thesesounds with fanatical (狂热的) but selfless authority.
Technique is of no use unless it is combined with musical knowledge and understanding. Greatartists are those who are so thoroughly at home in the language of music that they can enjoy performingworks written in any century.
Which of the following best states the main idea of the passage? A．It is easier to study medicine than music.
B．Painters and composers use totally different methods to reach the public.
C．All musicians must know how to time their own instruments.
D．Musicians must acquire technique and understanding to perform well.