Mary hides ramy's favorite toy under a blanket while ramy watches. ramy removes the blanket and squeals when he sees the toy. mary again hides the toy, but this time under a different blanket. even though ramy saw where mary hid his toy, he still looks under the first blanket before removing the second blanket and retrieving the toy. ramy has displayed
a. the a-not-b error correct
b. habituation
c. lack of object permanence
d. lack of centration

A - The A-not-B error.

Explanation:

This error, also known as perseverative, is mostly seen in infants around one year. By the time their are around 8 months they realize that objects that are hidden have still not dissapeared. It represents the ability that a child hass to represent said object in their mind. In this case, Ramy knows that the object still exists even if it's under a blanket. He will first look for it where he had founded it before even if he sees it's not there.