Which isotope has a relatively short half-life?

A: carbon-12

B: carbon-14

C: uranium-238

D: oxygen-16

Oxygen-16 and Carbon-12 are stableisotopes of elements O and C respectively. Hence, they do not have half-lives. But Carbon-14 andUranium-238 are radioactive isotopes. Among them Carbon-14 has relatively short half-life as about 5730 years while Uranium-238 has a long half-life as about 4.5 billion years.

Answer is. uranium-238