Answer:
Option-A
Step-by-step explanation:
Piaget proposed a theory related to the development of mind of a child in terms of cognitive abilities and suggested that the cognitive abilities of a child develop in stages and referred the theory as a cognitive theory of development.
Object permanence is one of the stages of the development of the cognitive abilities in which a child learns about the external world through his experience, knowledge and abilities.
In the given question, if the person is worried about the object permanence than he should be befitted from the studies conducted by the Piaget as his studies were mostly based on the scientific evidence.
Thus, Option-A is the correct answer.