A __________ is a means of building schemes in which an infant who has stumbled onto a new experience caused by his or her own motor activity tries to repeat the event again and again.
Correct Answer: B
Rationale: A circular reaction is a process where an infant repeats a specific action to explore and learn about the environment through their own motor activity. This repetition helps the infant to understand the consequences of their actions and build cognitive schemes. Sensorimotor reflex (choice A) refers to automatic responses to stimuli, not a purposeful repetition of actions to learn. Mental representation (choice C) involves internal cognitive structures to represent objects or events in the mind, which is different from the repetitive behavior described in the question. Goal-directed behavior (choice D) is purposeful and intentional, unlike the repetitive nature of circular reactions in infants' learning process.