Assertion (A) : Aurora is a curtain of color lights appear in the sky.
Reason (R): They are caused by magnetic storms in the upper atmosphere.
(a) Both A and R are individually true and R is the correct explanation for A.
(b) Both A and R are individually true but R is not the correct explanation for A
(c) A is true but R is false.
(d) R is true but A is false