Dolly, Molly and Polly each can walk at 6\:km/h. Their one motorcycle, which travels at 90\:km/h, can accommodate at most two of them at once (and cannot drive by itself!). Let t hours be the time taken for all three of them to reach a point 135\:km away. Ignoring the time required to start, stop or change directions, what is true about the smallest possible value of t?
Answer Choices
A. t<3.9
B. 3.9\le t<4.1
C. 4.1\le t<4.3
D. 4.3\le t<4.5
E. t\ge4.5