Answer: Object permanence
Explanation: Object permanence is the ability to understand the fact that object will have the presence even though it cannot be view or recognized. The perceiving of the object is usually in the form of seeing,viewing , hearing, sensing etc.
Vicki is also displaying object permanence ability by retrieving the doll which was out of her view because it fell behind her chair.She knows that it must have fallen out of her view but it can gained by searching.
Other options are incorrect because abstract reasoning is selection method to find missing pattern, egocentrism does not let a person create distinction between theirself and others.
Conservation is the protection of something for not leading to wastage.This, the correct option is permanence of object