The fourth unit took 10 hours to produce and the learning rate is expected to be 80 percent. How long will it take to produce the tenth? unit?
A. Greater than 8.0 hours but fewer than or equal to 9.0
B. Greater than 9.0
C. Greater than 7.0 hours but fewer than or equal to 8.0
D. Fewer than or equal to 7.0 hours