Final answer:
Danielle's nephew is demonstrating object permanence by acting as if the object covered by Danielle no longer exists, indicating that he hasn't yet fully grasped this concept. Object permanence is a key developmental milestone that typically emerges in the sensorimotor stage.
Step-by-step explanation:
Danielle's nephew is demonstrating object permanence when he acts as if a covered object is no longer there. Object permanence is the understanding that objects continue to exist even when they cannot be seen or heard. According to Jean Piaget, this is a concept that begins to develop in the sensorimotor stage of a child's cognitive development, which lasts from birth until about 2 years of age. Around the age of 5 to 8 months, children start to develop object permanence, which means an infant can remember an object after it has been removed from sight and will somehow indicate they know it still exists, often by attempting to look for it.
All the other options given, such as symbolic play, stranger anxiety, and parallel play, are different aspects of child development and do not apply to the situation described with Danielle and her nephew. Thus, when the nephew behaves as if the object Danielle has covered no longer exists, he reveals that he has not yet fully developed the awareness of object permanence.