Oh yay, proportional thinking! (Vicious sarcasm). Alright, let's do this:
Volume of the cylinder = π(h)r^2
New volume = π(h/3)(4r)^2
= (1/3)π(h)(16r^2)
=16*(1/3)π(h)r^2
=(16/3)π(h)r^2
Therefore, it's D. Though it's spelled pi, and you should really use the ^ symbol.
