Final answer:
None of the provided options matches the calculated age of the fossil, which is 18,000 years after three half-lives of carbon-14 at 6,000 years each. The closest given option is 'D. 12,000 years', but it is not correct according to the calculation.
Step-by-step explanation:
To determine the age of the fossil, we use the concept of half-life, which in the case of carbon-14 (C-14) is 5,730 years. However, the student provided the information using a 6,000-year half-life for simplicity. Starting with 80 grams of carbon, after each 6,000 years, the amount of carbon remaining would halve. We can calculate the number of half-life periods by using the following steps:
- First half-life (6,000 years): 80g / 2 = 40g
- Second half-life (12,000 years): 40g / 2 = 20g
- Third half-life (18,000 years): 20g / 2 = 10g
Since the fossil currently has 10 grams of carbon, it has gone through three half-lives. Therefore, 6,000 years x 3 = 18,000 years is the age of the fossil.
To provide correct option in the final answer, none of the options (A, B, C, D) matches the calculated age of 18,000 years. There may have been an error, or the correct option is not listed in the question. The closest answer, though still incorrect, would be 'D. 12,000 years' by the given choices, but keep in mind that according to the calculation, the correct age is 18,000 years.