[单选题]
In a nuclear reaction, what value is conserved inm/pe6; gn- +nccr qd,s7ygn/h addit0)pl5v mk x ;maw)ltfny9, i8wion to electric charge, energy, and moment9y 5wpf)w 8)mt0nvx mk, alil;um?
A. atomic number
B. neutron number
C. nucleon number
D. none of the given answers
