Answer:
c. Purchase cost of existing machine
Step-by-step explanation:
Relevant costs are the incremental costs that can be avoided by avoiding the functional activity with which the costs are associated.
Maintenance costs are relevant as they are directly linked to the use of machinery and as such are incremental with the use. The same is the case with the maintenance costs of the existing machine as they are avoidable if the new machine is purchased.
Expected cost savings would be incremental with the improved new machine. These cost savings thus are relevant.
Resale value of existing machine are also relevant as these would contribute towards the purchase of new machine.
The purchase price of existing machine is irrelevant as the machine cost has already been paid and regardless of purchasing the new machine or not, this cost is not a part of any calculations.
Hope that helps.