Answer:
The correct answer is option - B. tertiary circular reaction.
Explanation:
The sensorimotor stage is made up of 6 sub-stages that starts from birth and last up to 24 months. These 6 sub-stages are reflexes (0 to 1 month), primary circulation (1 to four months), secondary circular reactions (four to eight months), coordination of reaction (eight to twelve months), tertiary circular reaction (twelve to eighteen months) and lastly early representational thought (18 to 24 months).
The baby carter is in the tertiary circular sub stage of sensorimotor as it is the stage that is characterized by exploring and trying new actions. It is the fifth stage in which babies start the trial and error experimentation as carter walk around with box until he bumps his head.
Thus, the correct answer is option B. tertiary circular reaction.