Pedro Manufacturing is currently producing 100 units of a necessary component part by incurring $24,000 in direct materials, $10,400 in direct labor, $25,600 in variable overhead, and $17,600 in fixed overhead. If Pedro can purchase the units externally for $64,000, by how much would its total costs change?

A : $13,600 increase

B : $17,600 decrease

C : $4,000 increase

D : $64,000 increase