The correct answer is The majority of the 11-year-olds will state that the amount of water in the taller beaker is the same as in the original beaker.
Jean Piaget studied how knowledge (the genesis) and the evolution of human knowledge is born / formed until adolescence, seeking to understand the development of man's cognitive structures and the mental mechanisms that the individual uses to capture the world.
He investigated the process of knowledge construction and the logical structure that underlie learning, and in the last years of his life focused his studies on mathematical logical thinking.