D?
consider
1/(N-1) = (1/N)/(1-1/N) = 1/N + 1/N2 + 1/N3 + ...
if N = 10M we will have 1/N = 0.000...1 with M-1 leading zeros in the fractional part, thus the geometric series will give a repeating decimal expansion with fundamental period M, just as in the case for M = 19
now, with regards to restricting ourselves to those three technicalities, we simply require that our fundamental period M is prime, i.e. the only divisors are 1 and M itself, so that we don't end up having 'extra' technicalities
from M = 14 to M = 50 we see that 17, 19, 23, 29, 31, 37, 41, 43, 47 are prime, so there are at least 8 such possibilities eliminating A-C