Answer:
a. Formal thinkers would be more systematic when combining the liquids and eliminating combinations.
Explanation:
Formal operational thinker: They think abstractly through manipulating the ideas in the brain.
Formal operational stage: It begins around at the age of twelve and continues until adulthood. As soon as the adolescents enter in this stage, they acquire the ability to think and contemplate abstractly or conceptually by manipulating the ideas in their head, without depending on the concrete manipulation
Concrete operational thinker: They think in a flexible, logical, and organized manner.
Concrete Operational Stage. The stage continues from seven to eleven years of age, and is distinguished by the development of rationale and organized thinking.