
Answer:
C. Buy since the relevant cost to make it is $48.
Explanation:
Factor Co.
                        Make       Buy
Direct material            $ 8
Direct labor               24
Overhead                 40          24 ( Irrelevant Cost)
Cost of  Purchase                      46                       Â
Total product cost per unit $ 72 Â Â Â Â Â Â Â Â $ 70
Irrelevant costs are costs that continue whether the product is produced internally or purchased from outside. Here irrelevant costs are $ 24 that is 60 % of overheads.
The relevant cost to make it is $8+ $24+ $16(40-24)= $ 48
It is better to buy the product as it is a little financially advantageous. $2 per unit.