The following information relates to Cranmore Manufacturing: To produce a unit of product:

Cutting department	5 minutes per unit
Welding department	8 minutes per unit
Polishing department	3 minutes per unit
Finishing department	4 minutes per unit

There is a wait time of 5 minutes before the cutting department begins a batch, 15 minutes between the cutting and welding departments, a move and pre-wait between welding and polishing of 12 minutes, and a move and pre-wait between the polishing and finishing departments of 8 minutes. What is the production rate?

a.7.5 units per hour

b.12.0 units per hour

c.20.0 units per hour

d.15.0 units per hour