A pharmaceutical researcher is synthesizing spherical silica nanoparticles for drug delivery. If the average diameter of these spherical nanoparticles is decreased from 160 nm160\text{ nm}160 nm to 4 nm4\text{ nm}4 nm, by what factor does their surface area to volume ratio (SA/V\text{SA/V}SA/V) change?
It decreases by a factor of 404040.
It increases by a factor of 404040.
It increases by a factor of 160016001600.
It increases by a factor of 64,00064\text{,}00064,000.