[单选题]
In radioactive dating, ca:n vfk8tk7+sl5y7m9 q-iesqy rbon-tsnbb qfiv9fc3l*4s v,7 p 3i214 is often used. This nucleus emits a single beta particle when it decays. When thv3*p42 fbvincft9 s 3ilb ,s7qis happens, the resulting nucleus is
A. still carbon-14.
B. boron-14.
C. nitrogen-14.
D. carbon-15.
E. carbon-13.
