Final answer:
Clara is displaying an understanding of object permanence, which signifies cognitive development in infancy where a child learns that objects exist even when not visible.
Step-by-step explanation:
Baby Clara's favorite stuffed animal is placed under a blanket, and she looks under the cover to find it. Clara is demonstrating an understanding of object permanence, a cognitive development concept in which children learn that objects continue to exist even when they cannot be seen or heard. This realization typically occurs within the first 2 years of life as part of sensorimotor stage according to Jean Piaget's stages of cognitive development. Object permanence is an important milestone in the mental development of infants and toddlers, indicating their growing awareness of the world around them.