Since the figures are similar, we can establish a rule of three as follows.
We know that the area of the smaller figure is
, and its volume is 
. We also know that the area of the larger figure is 
; since we don't now its volume, lets represent it with 
:
We can conclude that the volume of the larger figure is
; therefore, the correct answer is a.
We know that the area of the smaller figure is
We can conclude that the volume of the larger figure is