Solar prominences
themselves are of no concern because they are visible in the Hydrogen Alpha
wavelength. They are anchored in place by magnetic fields. When these fields
break or reconnect, it can send the plasma that makes up the prominence away
from the sun. If one of these clouds impacts Earth, they are called CMEs or
coronal mass ejections. Depending on the magnetic orientation of the cloud with
respect to Earth's the CME can break down our magnetic field resulting in
geomagnetic storms, aurorae, power grid fluctuations, and particle radiation
near the poles, satellite single upset events, and radio blackouts.
Thus, letter a is the answer.
