In the Visual Cliff Paradigm, when babies see their mothers display a happy/smiling face, what did they do?
A. Approach the mother, off the visual cliff because they felt safe
B. Approach the mother, off the visual cliff, but only when the experimenter was not present
C. Stay away from the visual cliff because they developed enough depth-perception ability by this age to rely on their own stimuli perception over their mother's facial cue
D. Stay away from the visual cliff, but if the mother additionally verbally expressed a positive emotion/encouragement, they approached off the visual cliff