For centuries, the nature of the brain was shrouded in mystery. Aristotle is said to have 1 it was a cold sponge, whose main task was to 2 the blood. Later, Leonardo da Vinci 3 the brain as a curious void filled by three tiny bulbous structures 4 in a straight line 5 the eyeball. 　　Not all early theories were quite so misguided, 6 . From the first studies 7 language deficits, it was 8 that the brain played some direct part in language use. In 1836, an 9 French country doctor, Max Dax, claimed that, in forty aphasic (患失语症的) patients he had seen, 10 of language ability always 11 with damage to the left half of the brain. Thirty years later, this claim was 12 proved by the French surgeon Paul Broca. He had studied aphasic 13 in patients who were found to have brain damage 14 the left frontal lobe. Broca was struck by the contrast with right hemisphere damage, 15 seemed to have little effect on speech. The area Broca isolated and the aphasia associated with it now 16 his name, "Broca’’s aphasia." 　　Ten years after Broca’’s 17 , Karl Wernicke, a young researcher in Germany, made another startling 18 , which ultimately 19 him to propose not just a new language area, but an overall theory of 20 language is handled in the brain.

A． it
B． that
C． which
D． what