Let S = {a, b, c, d, e, f, g} be a collection of objects with benefit-weight values, a: (12,4), b: (10,6), c: (8,5), d: (11,7), e: (14,3), f: (7,1), g: (9,6). What is an optimal solution to the 0-1 knapsack problem for S assuming we have a sack that can hold objects with total weight 18? Show your work.