According to the passage, Michelangelo was unable to finish three-fifths of his artworks for which of the following reasons
A. He possessed a deep sense of ambiguity toward his own ideas that caused him to lose confidence in them. B. He displayed a tendency to work quickly on one project and then abandon it in haste for another. C. He generally felt a dissatisfaction with the ideals that served as the model for his art works. D. He frequently felt unable to express his general ideals through a particular art work. E. A heavy price was exacted upon him as an artist by the process of continual abstraction.