(1) n/5 has one prime factor. So n could be 25 or 15, in which case n/5 = 5 or n/5 = 3, so n can have more than one prime factor. So Insufficient.
(2) 3*n^2 has two different prime factors. So if n = 5*3 = 15, or n = 5 or 25, then also the expression has two distinct prime factors. So Insufficient.
In (1) and (2), 15 can work, or 25 can work, so answer is E.
Formula of Life -> Achievement/Potential = k * Happiness (where k is a constant)
GMAT Club Premium Membership - big benefits and savings