According to the mutual-regulation model regarding emotional states,

A) parental actions determine an infant's emotional state until about 9 months of age.
B) babies as young as 3 months regulate their own emotional state to some degree.
C) low-birth-weight babies require extra stimulation for proper emotional development.
D) emotional states of the mother do not affect those of the infant.

The mutual-regulation model suggests that by 3 months of age, infants begin to regulate their own emotional states to some degree. This means that infants can start to soothe themselves, or seek comfort from caregivers, in response to different emotional experiences. Parental actions still play an important role in supporting emotional regulation, but babies are not entirely dependent on their caregivers to manage their emotions.