In math class, eleven-year-old Dylan was asked by his teacher, "If Mary is taller than Darryl and Darryl is taller than Evan, who is the tallest?" This question perplexed Dylan, and he asked the teacher for a pen and paper to draw a picture so he could attempt to answer. Sociologists would argue that this question is too abstract for Dylan to answer, and this shows that he is in which stage of development?