Robots can make a train in 6 days working 5 hours a day. In how many days will 25 robots, working 6 hours a day complete the same work

15 robots can make a train in 6 days working 5 hours a day. In how many days will 25 robots, working 6 hours a day complete the same work? (Assume that all robots work at the same rate)

A. 18 days
B. 9 days
C. 6 days
D. 3 days