[单选题]
If an element of atomic number 15 xg7j:qub5)l-cp yf70dfk+zuhas an isotope of mass number0d5 v y+mi;rzlyy:.5hrd; clc 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.