Final answer:
Children learn to retrace their thoughts and see more than one dimension to a problem, but cannot yet handle abstract concepts during the concrete operational stage, option B.
Step-by-step explanation:
According to Piaget, children learn to retrace their thoughts, correct themselves, see more than one dimension to a problem, but cannot yet handle abstract concepts during the concrete operational stage. The correct option is B. Concrete operational stage.
In the concrete operational stage, which occurs from about 7 to 11 years old, children have developed the ability to think logically about real (concrete) events. This stage is characterized by a grasp on the use of numbers, the ability to employ memory strategies, understanding of mathematical operations, and mastery of the concept of conservation. At this point, children can logically solve problems that are tangible or have been experienced concretely, yet they are not yet capable of dealing with hypothetical or abstract situations which is a feature of the subsequent formal operational stage.