Margaret, who is 4, is upset because her older sister Leslie "has more candy." Actually, each girl has one caramel, but Leslie has stretched hers into a long string while Margaret's is still a small cube. This shows Margaret's inability to

This shows Margaret's inability to conservation.

Explanation:

In the field of psychology, conservation can be described as the thinking of the person that a certain quantity of something will remain the same even if adjustments in the size or shape are made.

The same phenomenon of conservation was observed in Margaret because she believed that her candy will be lesser than Leslie's even though Leslie had made an adjustment in the size and shape of her candy.