Consider the series n=1∑∞knn!nn with k>0. For which values of k does the series converge?
a) It converges when k≥e and diverges when k<e.
b) It converges when k>e and diverges when k≤e.
c) It converges when k>1 and diverges when k≤1.
d) It diverges for all positive k.