Answer
Choice D.
Work Step by Step
Carbon-14 has a half-life of about 5730 years. After each half-life, another one-half of the remaining C-14 nuclei will decay. So, after 10 half-lives less than $\frac{1}{2^{10}}$, or less than a part in a thousand of the original C-14 remains.
C-14 dating is not a useful technique for measuring time periods that are hundreds of thousands of years or longer.
