The river . . . . . very fast after this rain stops. A. flows B. will be flowing C. is flowing D. has flowed

The correct answer is: B. will be flowing

The river will be flowing very fast after this rain stops because the rain will cause the river to swell. The river will be flowing very fast because the water will be rushing down the river to the ocean.

Option A, “flows,” is incorrect because the river is not currently flowing very fast. Option C, “is flowing,” is incorrect because the river will not be flowing very fast until after the rain stops. Option D, “has flowed,” is incorrect because the river has not yet flowed very fast.