While Playing with Some Candy,3-Year-Old Ruth Places Five Chocolate Pieces

Multiple Choice

While playing with some candy,3-year-old Ruth places five chocolate pieces in one row and another five pieces in an identical row.She then accidentally pushes the end piece of candy in row one away from the rest.After staring at this new "longer" row,she decides to eat it because,"it now has more candy." Ruth's thinking is explained as the result of the inability to conserve

A) area.
B) length.
C) number.
D) volume.