Casey Likes to Play with Blocks and He Has Several

Casey likes to play with blocks and he has several different kinds: square wooden ones, large waffle-like ones, small plastic ones that easily interlock, as well as a variety of other types. At first Casey just referred to these objects as "blocks." Now, when his mom suggests he play with his blocks, he replies, "Which ones?" Piaget would interpret his response to indicate that Casey

A) has assimilated different types of blocks into his schema for blocks.
B) has accommodated his schema for blocks to differentiate among types of blocks.
C) has memorized the different types of blocks available.
D) has forgotten that he has blocks.