Four-month-old Nanette is staring dreamily at the mobile above her rocker seat. Chris wants to show her brother Jack how cute it is, so they quietly stand to the side and watch. When Jack sneezes, Nanette turns her head toward them and the spell is broken. The baby is demonstrating_________.
A) the startle response
B) sound localization
C) the Babinski reflex
d) aural acuity