Which of the following explains why a 13-month-old boy will respond negatively to a harsh look on his mother's face, but will respond neutrally to a harsh look on a stranger's face?

The child understands the language of his mother much earlier than he
understands the language of strangers.
The child has made a connection to previous harsh expressions and tones
of voice from his mother.
The child has an insecure attachment to his mother, so he is more afraid of
her than he is of the stranger.
Children do not recognize differences in faces until they are at least 18
months old.

The child has made a connection to previous harsh expressions and tones
of voice from his mother.