【步筱昕】評論
细节题。还是看第一段,As the cards change from one to the other,her gaze(凝视) starts to lose its focus - until a third, with three black spots, is presented. Her gaze returns: she looks at it for twice as long as she did at the previous card.卡片改变时,直到出现3个黑点纸板时,婴儿又开始集中注视了。由此可知,婴儿对于有不同数目黑点的纸板比较敏感。因此,正确答案为D。