Final answer:
An object with 25% of the C-14 activity of a living organism has gone through two half-lives. One half-life of C-14 is 5730 years, so the object would be approximately 11,460 years old.
Step-by-step explanation:
The question relates to using C-14 dating to determine the age of an object based on its residual radioactive activity as compared to a living organism. If an object has only 25% of the radioactive activity of C-14 that a living organism has, it indicates that the object has gone through two half-lives since C-14 decays to 50% in one half-life of 5730 years. Therefore, after two half-lives (5730 years x 2), the object would be around 11,460 years old.