[单选题]
If an atom's atomic number ism7tgh c/ 7m::iquu)ik given b u ;g03rf -ar*pbry fwxup07x5y Z, its atomic mass by A, and its neutron number by N, which of the fo y arfx5 b*x7 prfw0;u3p0ur-gllowing is correct?
A. N = A + Z
B. N = Z - A
C. N = A - Z
D. none of the given answers