For all stable nuclei with a large mass number, the ratio of the number of neutrons (Nn) to the number of protons (Np), Nn/Np, is:
a. equal to 1
b. greater than 1
c. unrelated to the stability of nuclei
d. almost the ratio 1/2
e. slightly less than 1
f. equal to the ratio of the neutron-mass to the proton-mass