Please help me on the 3rd question

Which of the data provided in the table is a sunk cost? the annual cash operating costs of the old machine the annual cash operating costs of the replacement machine the disposal value of the old machine the original cost of the old machine For the decision to keep the old machine, the relevant costs of keeping the old machine total: $120,000 $70,000 $94,000 $144,000 The difference between keeping the old machine and replacing the old machine is: $74,000 in favor of keeping the old machine $24,000 in favor of keeping the old machine $74,000 in favor of replacing the old machine $24,000 in favor of replacing the old machine