Which best corrects the run-on sentence? Auroras illuminate the northern horizon they have a greenish glow or sometimes a faint red one.
a. Auroras illuminate. The northern horizon in a greenish glow and sometimes a faint red one.
b. Auroras illuminate the northern horizon. With a greenish glow or sometimes a faint red one.
c. Auroras illuminate the northern horizon. They have a greenish glow or sometimes a faint red one.
d. Auroras illuminate the northern horizon, a greenish glow or sometimes a faint red one.