Answer:
object permanence.
Explanation:
Object permanence is used to describe the situation were infants knows that an object continues to exist even when they are not seeing it.
Baby Radsheda is yet to develop her object permanence, that was why she opted for crying rather than looking for her pacifier.
A child that have developed her object permanence will search for any object she is playing with once it goes missing, this is because she believes the object exists.