Which Demonstrates the School-Age Child's Developing Logic in the Stage

Which demonstrates the school-age child's developing logic in the stage of concrete operations? Select all that apply.

A) The school-age child is able to recognize that 1 lb of feathers is equal to 1 lb of metal.
B) The school-age child is able to recognize that he can be a son, brother, or nephew at the same time.
C) The school-age child understands the principles of adding, subtracting, and reversibility.
D) The school-age child has thinking that is characterized by egocentrism, animism, and centration.