50. Halley's comet moves about the Sun in an elliptical orbit with its closest approach to the Sun being 0.59 A.U. and its farthest distance being 35 A.U. If the comet's speed at closest approach is 54 km/s, what is its speed when it is farthest from the Sun? [1 Astronomical Unit (A.U.) is the Earth-Sun distance.] (A) 3203 m/s (B) 910 m/s (C) 15 m/s (D) 13 m/s (E) 7011 m/s