Materials A, B, and C are solids that are at their melting temperatures. Material A requires 200 J to melt 4 kg, material B requires 300 J to melt 5 kg, and material C requires 300 J to melt 6 kg. Rank the materials according to their heats of fusion. If multiple materials rank equally, use the same rank for each, then exclude the intermediate ranking (i. e. if objects A, B, and C must be ranked, and A and B must both be ranked first, the ranking would be A:Greatest, B:Greatest, C:Third greatest). If all materials rank equally, rank each as 'Greatest'.