The correct answer is C) 60 tons. The key information here is that the cranes have a 30 ton capacity in single mode. In twin mode, where two cranes are used together, the combined capacity is doubled to 60 tons. This is a standard industry practice for pedestal cranes, where the twin mode capacity is equal to the sum of the individual crane capacities. The other options are incorrect because: A) 15 tons is only half the actual twin mode capacity. B) 30 tons is the single mode capacity, not the twin mode capacity. D) 120 tons exceeds the reasonable capacity for 30 ton cranes even in twin mode.