[单选题]
97.40: A boat is travelib1:ex9+ulc xv n+c, 0twxh m9ah7rss1h ll.y8e .mne0 sg at 6.0 km/h $30^{\circ}$ W of N with respect to a river. The river is flowing at 3.0km/h from W to E. As observed from shore, the boat is traveling
A. $45^{\circ}$ E of N
B. $30^{\circ}$ E of N
C. due N
D. $30^{\circ}$ W of N
E. $45^{\circ}$ W of N
