Answer:
Jessica has developed Object Permanence.
Explanation:
Understanding the object permanence concept is a major developmental milestone for a baby, as it will help the baby understand the world and know what to expect next. This means the baby will stop being frightened when he gives something to someone - such as a toy - because he will know that it can be retrieved. In addition, the baby will also realize that people exist even when they are away. Before reaching this level of development, the baby did not have the ability to understand this - when the mother left, he thought she was gone, that she had ceased to exist. However, by reaching this milestone, even if the baby is not happy with the mother's departure, the baby may realize that the mother still exists and will return.
