At noon, Boat A is at a dock and begins sailing due east at a constant speed of 10 km/h. At the same moment, Boat B is 40 km due north of the dock and sails due south at 6 km/h. Assuming both boats travel in straight lines, at what time t (in hours after noon) is the distance between the two boats minimized?
a) t≈2.5 h
b) t≈1.8 h
c) t≈0.88 h
d) t≈3.5 h