Concept:Piaget’s formal operational stage involves hypothetical, multidimensional, and systematic thinking.
Explanation:According to Piaget, cognitive development occurs in four fixed stages.
These stages are: sensorimotor, pre-operational, concrete operational, and formal operational.
In the sensorimotor stage (0–2 years), children learn through senses and reflexes.
In the pre-operational stage (2–7 years), thinking is egocentric and irreversible.
In the concrete operational stage (7–11 years), logic, classification, and conservation develop.
In the formal operational stage (11–15 years), children begin to think abstractly and scientifically.
At this stage, children can test hypotheses systematically and consider multiple dimensions of a problem.
They also use deductive logic and think about possibilities rather than only concrete objects.
Thus, the ability to solve problems by testing hypotheses and thinking multidimensionally is the key feature of the formal operational stage.
This matches the description given in the question exactly.
Answer:C. Formal operational stage