Which of the following statements is TRUE according to this passage？A．The achievements of

Which of the following statements is TRUE according to this passage？

A．The achievements of stage four are based on the ones of the previous three stages.

B．Symboling is the characteristic of each of the four stages of development.

C．The two aspects of the evolution of minding are symboling and articulate speech.

D．The factor of referring meanings of things involved is significant in all the four stages of development.