Natasha's Interior Designs has support staff for its professional designers. The two professionals work a total of 1,800 hours each and make $45,000 each per year. The total support budget is $90,000, of which $60,000 is professional support, and $30,000 is general office overhead. A job requiring 30 professional hours should be billed how much for overhead if a simplified costing approach is used and hours is the cost driver?

a. $750

b. $30

c. $600

d. $25