During which Piagetian stage are conservation concept studies MOST revealing of children's limitations?

preoperational

Explanation:

Preoperational stage: In psychology, the preoperational stage is one of the stages in the theory of cognitive development and is considered as the second stage which starts from the age of two years and lasts through the age of seven years.

The preoperational stage's theory was proposed by Jean Piaget who studies how a child grows through different cognitive stages. At this stage, a child learns to talk, manipulates symbols, and symbolic representations. A child uses different symbols to denote images, ideas, and words.