How would Germans know where the B17 Bombers were in the sky?

At night, they used search lights and radar.

Explanation:

This lit up the B-17 Flying Fortresses. Also they had radar too. This would spot the bombers. Not to mention, the luftwaffle, (German Air Force) were on guard ready to intercept the planes and take the down. They were 95%of the time  prepared to take out the B-17 Flying Fortresses.

answer; ///i believe that the correct answer is (a) the great depression

the second significant cause of the great migration was the desire of black southerners to escape segregation, known euphemistically as jim crow. rural african american southerners believed that segregation - and racism and prejudice against blacks - was significantly less intense in the north.