The Exact Visual Acuity of an Infant Is Determined by the Point

The exact visual acuity of an infant is determined by the point at which she/he

A) begins to look longer at a grey picture than at a black and white bull's eye.
B) can detect the difference between a card that is blue from one that is grey.
C) can habituate to a striped card.
D) can no longer detect the difference between a card with narrow and compressed black and white stripes from one that is plain grey.