Tom K. answered 03/10/21
Knowledgeable and Friendly Math and Statistics Tutor
A,D, and B for all n >= 3 is bounded below by 1/n, which is divergent, so they are divergent.
As e^(n^2) > n^4 for all n, n^2/e^(n^2) is bounded above by 1/n^2, which is converges, so this converges.
C Converges
(another way to show C is to show that the ratio goes to 0)