Select the best answer for the given question from the options:
Assertion (A): Metals low in the reactivity series are very unreactive. The oxides of these metals can be reduced to metals by heating alone.
Reason (R): Cinnabar, when heated in the air, first gets converted into a mercuric oxide, which is then reduced to mercury on further heating.
Reason (R): Cinnabar, when heated in the air, first gets converted into a mercuric oxide, which is then reduced to mercury on further heating.