Which of the following solar phenomena is likely to have the most negative impact on earth? asa

The answer is A solar flare as it may cause brief radio blackouts. Aurora = northern lights. Look it up, the word aurora and see what comes up. : )
The last isn't true. For satellites, it may be true above the atmosphere, but certainly not within the earth; airplanes don't fly that high, so it's referring to within the atmosphere.