From the Perspective of Piaget's Theory, Why Is Language Critical

From the perspective of Piaget's theory, why is language critical for children's cognitive development?

A) It allows them to get what they want.
B) It gives them a means for thinking about things symbolically.
C) It takes up most of their mental energy, thereby keeping them from being easily distracted.
D) It gives them a better self-image, because they are now aware that they can communicate effectively with other human beings.