[单选题]
A swimmer heading directl tscsm.;utijtk (97-12uj akib )bvh9y across a river 200 m wide reachesgjr ine+7 aj7r+909nv2 q nylf the opposite bank in 6 min 40 s. 09jl2y9ni f+q vjar7+grne7 nShe is swept downstream 480 m. What is the speed of the current?