What Are Coronal Holes

What are coronal holes?

A) regions on the photosphere where magnetic lines poke through,creating the cooler areas of the sunspots
B) areas of the corona where magnetic field lines project into space,allowing charged particles to escape the Sun,becoming part of the solar wind
C) holes in the corona of the Sun that allow us to see the photosphere
D) tunnels in the outer layers of the Sun through which photons can escape more quickly than through the radiation zone
E) all of the above