Which of the following artists was/were the pioneer(s) of Cubist art

A．believed that an artist should play an important role in discovering different forms of expression
B．began with traditional ways of painting and changed to explore his own creative ways later
C．developed his own style of painting from the very beginning of his career as an artist
D．could see every subject in a way different from others

A．one has only himself to blame for not being able to understand a thing
B．it is always difficult for an ordinary man to accept a modern, revolutionary kind of art
C．everybody should be able to learn to appreciate the surrealist art
D．for people who can't understand the surrealist art, the problem lies in themselves instead of the artist adopting this style