[单选题]
If an atom's atomic o )isqtl+t(*k 27-vqvodu- hnnko/s:e6y 1 gbyumber is given by Z, its atomic mass by A, and its neutron number by N, which of t:sg1ok /bey 6yhe following is correct?
A. N = A + Z
B. N = Z - A
C. N = A - Z
D. none of the given answers