A radioactive nucleus emits 3 alpha particles and 2 positrons. For the resultant nucleus, the ratio of neutrons to protons is (consider the initial nucleus to have atomic number Z and atomic mass A):
1
(A - Z - 8)/(Z - 4)
2
(A - Z - 4)/(Z - 8)
3
(A - Z - 4)/(Z - 2)
4
(A - Z - 12)/(Z - 4)