I : Roots : : House : II     I.   [A] Flower 

I : Roots : : House : II
I. [A] Flower [B] Tree [C] Branches [D] Truck
II. [P] Foundation [Q] Walls [R] Floor [S] Platform

A. AQ

B. BP

C. CS

D. DR

Answer: B . BP

Justification:

Second is the lowest part of the first.