Dev has been sucking his thumb for a few weeks.His parents would prefer him to use a pacifier,so they begin to offer one,but Dev rejects it and continues to suck his thumb.Dev is at stage _____ of Piaget's theory of sensorimotor development.

A) one
B) two
C) three
D) four

Dev is likely in stage two of Piaget's sensorimotor development, which is the primary circular reactions phase (1-4 months). During this stage, infants start to repeat actions that are pleasurable or bring about a desirable outcome, like thumb sucking for comfort. Dev's preference for thumb sucking over a pacifier suggests he's engaging in behaviors that are self-soothing, a characteristic of this stage.