Which of the following statements is true regarding a dielectric material in the context of physics?
a) A dielectric material conducts electricity more efficiently than a conductor.
b) A dielectric material reduces the capacitance of a capacitor when inserted between the plates.
c) A dielectric material increases the capacitance of a capacitor when inserted between the plates.
d) A dielectric material has no effect on the electric field between the plates of a capacitor.