Answer: Formal operational
Explanation:
In terms of Piaget, formal operational level is the stage in which a person tends to think in abstract manner.They also gain the ability of ego-centrism and planning things.They can also argue on matters, reason as well as regulate and manipulate thoughts.
According to the question,Davina at formal operational stage as per Piaget theory.She has ability to understand material of science class ,can perform reasoning on material.
