TOEFL Reading: ETS-TOEFL阅读机经 - GB5A73TQY8_7ZJ30L$

Why does the author provide the information that "When one of Vermeer's paintings was X-rayed, it did not have any preliminary sketches on the canvas beneath the paint, but rather the complete image drawn in black and white without any trial sketches?" A. To provide an example of a way to learn about the practices of artists who did not keep good records B. To emphasize Vermeer's confidence and skill as an artist C. To provide evidence that Vermeer may have traced the image using a camera obscura D. To argue that Vermeer did his preliminary sketching on paper, rather than on canvas