Each of the three people individually can complete a certain job in 4, 5, and 8 hours, respectively. What is the lowest fraction of the job that can be done in 1 hour by 2 of the people working together at their respective rates?	Pick:
A) 9 / 20	B) 11 / 20	C) 11 / 32	D) 13 / 40	E) 17 / 40

Rationale: "the two slowest people work at rates of 1 / 5 and 1 / 8 of the job per hour . the sum of these rates is 1 / 5 + 1 / 8 = 13 / 40 of the job per hour . the answer is d ."
Answer: D