Fossils are dated by `:`

Options

A. Stratigraphic position
B. Amount of calcium residue
C. Association with other animals
D. Radio-active carbon from

Answer

**Step-by-Step Solution:**

1. **Understanding Fossils**: Fossils are the preserved remains or traces of organisms that lived in the past. They can provide valuable information about the history of life on Earth.

2. **Dating Fossils**: To determine the age of fossils, various methods can be used. The question asks for the specific method used to date fossils.

3. **Examining Options**:
- **Stratigraphic Position**: This refers to the layer of rock in which a fossil is found. While it can provide context about the relative age, it does not give an exact date.
- **Amount of Calcium Residue**: This is not a recognized method for dating fossils.
- **Association with Other Animals**: This can help in understanding the environment but does not provide a specific date.
- **Radioactive Carbon Dating**: This is a well-established method used to determine the age of organic materials, including fossils, by measuring the decay of carbon-14 isotopes.

4. **Conclusion**: The most accurate method for dating fossils, especially those up to 50,000 years old, is radioactive carbon dating.

5. **Final Answer**: Fossils are dated by radioactive carbon dating.

---