Mulcahey Automobiles Company fabricates automobiles. Each vehicle includes one wiring harness, which is currently made in-house. Details of the harness fabrication are as follows: Volume Variable cost per unit Fixed costs 800 units per month $7 per unit $12,000 per month An Indonesian factory has offered to supply Mulcahey with ready-made units for a cost of $15 per wiring harness. Assume that Mulcahey's fixed costs could be reduced by $4,000 if it outsources and that Mulcahey will not be able to use the excess capacity in any profitable manner. If Mulcahey decides to outsource, monthly operating income will decrease by $2,400 increase by $5,600 decrease by $12,000 increase by $12,000