The correct answer is a. Knowing that even if you change the appearance of something, it is still equal in size as long as nothing has been removed or added.
According to the psychologist, Jean Piaget, conservation is a cognitive ability that children acquire around age 7-11. Conservation refers to the knowledge that the quantity of something does not change despite its appearance, layout or orientation being modified. The ability to conserve is significant because it is the beginning of children's ability to think logically.