The ability of both infants and caregivers to respond appropriately to the signals about each other's emotional states is known as

A) secure attachment.
B) mutual regulation.
C) a facial paradigm.
D) infant intimacy regulation.

Mutual regulation refers to the ability of both the infant and caregiver to respond to each other's emotional states, which supports healthy attachment and development. Secure attachment refers specifically to the quality of the attachment relationship, while facial paradigm and infant intimacy regulation are not commonly used terms in developmental psychology.