It took Nasrin two hours and thirty minutes to canoe the 4.5 \mathrm{~km} into her camp. Paddling much faster, the return trip took her \frac{1}{3} of the time. What was Nasrin’s mean (average) speed as she paddled to camp and back?
Answer Choices
A. 1.25 \mathrm{~km} / \mathrm{h}
B. 3.96 \mathrm{~km} / \mathrm{h}
C. 1.8 \mathrm{~km} / \mathrm{h}
D. 1.95 \mathrm{~km} / \mathrm{h}
E. 2.7 \mathrm{~km} / \mathrm{h}