Final answer:
Sunspots are a result of the Sun's electromagnetic field, caused by strong magnetic fields that block heat convection, creating cooler, darker spots on the Sun's surface.
Step-by-step explanation:
One effect of the Sun's electromagnetic field is the formation of sunspots. Sunspots are temporary phenomena on the Sun's photosphere that appear as spots darker than the surrounding areas. They are cool because strong magnetic fields block the outward flow of energy. The Sun's dynamo generates these magnetic fields through the churning of turbulent layers of ionized gas within the Sun's interior. This generates electric currents, or moving electrons, which in turn create magnetic fields. These strong magnetic fields can then block the convection of heat to the surface, resulting in cooler, dark spots known as sunspots.
Thus, the correct answer is: C) Sunspots.