John asks why the last step of Pólya's four-step problem solving process, looking back, is necessary since he has already given the answer. What can you tell him?
Select all the possible reasons the last step, looking back, is necessary below.
A. Looking back allows a student to check that the answer is correct.
B. Looking back allows a student to determine the best strategy to find the solution.
C. Looking back allows a student to understand the problem.
D. Looking back allows a student to check that the answer makes sense in context of the problem.