Parker Manufacturing makes six models of widget. One model, the Standard, has a total per-unit cost of $6.20. Each Standard requires $1.10 of materials and takes 0.4 direct labor hours to manufacture. The firms costs per direct labor hour are $9. Total costs for each model of widget consist of direct labor costs, materials costs, and overhead costs. If Parker allocates overhead on the basis of direct labor hours, what is the firms predetermined overhead rate?

A. $3.75 per direct labor hour

B. $1.50 per direct labor hour

C : $9.00 per direct labor hour

D : $5.40 per direct labor hour