The four sentences labelled A, B, C and D, given below in jumbled order, together form a coherent paragraph. Arrange the sentences in the most logical order and choose the sequence that produces the best paragraph.

A. That belief collapsed in 1997, when a chess computer defeated the reigning world champion in a full match.
B. For most of the twentieth century, chess masters believed that no machine could ever match human intuition at the board.
C. Today, even club players train with engines, treating the software as a sparring partner rather than a rival.
D. Instead of abandoning the game, professional players began to study the machine's strange but powerful ideas.