[单选题]
In radioactive dating, v hvi1 dgrxpxyln,3u8qek; ; 6y8k..ncarboi, ojgtvak9 0a2m5/+vpjul5s n-14 is often used. This nucleus emits a single beta particle when it decays. Ws+ajo5 atl25jv/u0kvim g9 p, hen this happens, the resulting nucleus is
A. still carbon-14.
B. boron-14.
C. nitrogen-14.
D. carbon-15.
E. carbon-13.
