Eight-Year-Old Eric Watches as You Flatten One of Two Equal-Sized

Multiple Choice

Eight-year-old Eric watches as you flatten one of two equal-sized balls of clay into a pancake. Eric says they both still have the same amount of clay. When he is asked how he knows that the ball and the pancake have the same amount of clay, he points out that the pancake could once again be rolled up into a ball, demonstrating that he ​

A) is now in the preoperational stage.
B) understands the concept of reversibility.
C) is unable to decenter.
D) is no longer egocentric.