单项选择题John can mow a field in 6 hours.Bill can mowa field in 5 hours.Henry can mow a field in 4 hours.Joe can mowa field in 3 hours.Tomcan mowa field in 2 hours.If they all work together at their respective rates, how long will it take to mow the field
A.1.4 minutes
B.39.4 minutes
C.40.4 minutes.
D.38.4 minutes.