Imagine two systems designed to check the work of an AI solving a multi-step mathematical problem. System A's verifier checks if each individual step (e.g., '2+2=4') is mathematically correct on its own. System B's verifier evaluates each step based on whether it is part of a promising path towards the final correct answer, even if it's a less common but more efficient step. Explain the fundamental difference in the evaluation criteria between these two verifiers and identify which one operates on the principle of forecasting future utility.