Answer:
The correct answer is C. Xander has not yet attained object permanence.
Explanation:
According to Piaget's Stages of Cognitive Development, object permanence occurs during the Sensorimotor Stage (birth- 2 years old), in which an infant understands that an object is still there even if it cannot be seen.
In this case, Xander has not yet obtained object permanence since as soon as the rattle is taken away, for him it has ceased to exist, thus making him be interested in other stimulus.