How Do We Know That the Mirror Task Shows an Infant's

How do we know that the mirror task shows an infant's emerging sense of self and not their growing understanding of mirrors?

A) When infants verbalize during the mirror task, they are likely to say their name.
B) Children show no understanding of mirrors until they are at least 4 or 5.
C) Infants who have never seen mirrors show the same pattern of results.
D) We don't.