Step 1: A greedy method gives an optimal answer only when picking the best local choice at each step leads to a globally best solution.
Step 2: In the Fractional Knapsack Problem you may take fractions of an item. Sort items by value per unit weight \( \tfrac{v_i}{w_i} \), then keep adding the highest ratio item, taking a fraction of the last one to fill the bag. This greedy rule is proven optimal.
Step 3: The other three fail. The Traveling Salesman Problem is NP-hard and greedy nearest-neighbour is not optimal. Matrix Chain Multiplication needs dynamic programming to find the best parenthesization. The 0/1 Knapsack forbids fractions, so greedy by ratio can miss the best set.
Step 4: The correct answer is the Fractional Knapsack Problem, option A.