Although 8-year-old Claire can easily arrange sticks of differing lengths from shortest to tallest, she cannot solve the following problem: "Jack is taller than Sam, and Sam is taller than Max. Who is the tallest?" This is because Claire's concrete mental operations work poorly with

Seriation.

Explanation:

In the third stage of Piaget's theory of Cognitive development i. e., Concrete Operational Stage, Seriation is an important process. The third stage in this theory covers the age of 7-12 years.

Seriation is the ability of a child to sort objects according to its characteristics.

Claire who is 8-years-old is able to sort sticks according to its size by seeing there features or sizes but unable to solve the problem of who is tallest because his concrete mental operation is poor in seriation.

So, the correct answer is "seriation".