Lightning : I : : II : Sky     I.   [A] Cloud 

Lightning : I : : II : Sky
I. [A] Cloud [B] Rain [C] Rainbow [D] Sky
II. [P] Rain [Q] Wind [R] Thunder [S] Rainbow

A. AS

B. BR

C. CQ

D. DP

Answer: A . AS

Justification:

Lightning occurs in clouds and rainbow is formed in the sky.