The Fact That Babies as Young as 2 Months of Age

The fact that babies as young as 2 months of age will kick their leg in order to make a mobile jump suggests that

A) even very young infants can be classically conditioned.
B) babies will emit behaviour simply to produce an interesting sight.
C) in order to serve as a reinforcer for infants, a consequence must satisfy a biological need.
D) habituation emerges very early in infancy.