Concrete operational stage is the correct answer.
Jean Piaget was a phychologist very well-known for his contributions to the child development studies. According to him, there are four stages of cognitive development, the concrete operational stage is one of them. During the third stage, also known as concrete operational stage, 8-11 year olds develop cognitively by using logic that is based on concrete evidence. However, even though these kids are able to learn to retrace their thoughts, correct themselves and see more than one dimension to a problem, most of them still struggle handling abstract concepts.