Which among the following is a stable isotope of C?
1. ${}^{12}C$ 2. ${}^{13}C$ 3. ${}^{14}C$

The correct option is B Only 1 and 2
Naturally occurring carbon contains three isotopes- ${}^{12}C,{}^{13}C,{}^{14}C.$
Only ${}^{12}C,{}^{13}C$ are stable isotopes.