[单选题]
If an element of atomi japklvk 8,--v2iunz 3c numberb-bvribe41) 6: k igog*pqnb+ 15 has an isotope of mass number 32,
A. the number of neutrons in the nucleus is 15.
B. the number of neutrons in the nucleus is 17.
C. the number of protons in the nucleus is 17.
D. the number of nucleons in the nucleus is 15.
