Carolyn Rovee-Collier's Research Used a Moving Mobile or a Moving

Carolyn Rovee-Collier's research used a moving mobile or a moving train to assess infant memory. This research shows

A) a steady improvement in memory during the first 18 months of life.
B) no consistent pattern in memory development because the measure of memory used for the first 6 months yields very different data from the measure of memory used later in infancy.
C) a very low level of correct responses during the first 6 months, because infants' brain development is incomplete, followed by a very rapid increase in memory.
D) a very rapid increase in memory during the first 6 months, followed by a more gradual increase and then a plateau.