[单选题]
Isotopes of an element l(; l/pvr tc*shave nucleip5e fus4-jo.icmr -b+ with
A. the same number of protons, but different numbers of neutrons.
B. the same number of protons, and the same number of neutrons.
C. a different number of protons, and a different number of neutrons.
D. a different number of protons, and the same number of neutrons.