A. Fossils are remains of hard parts of life forms in Rock.
B. A study of fossils in different sedimentary layers indicates the geological period in which they live.
C. Radio isotopes are often used to determine the age of the fossils
D. Study of fossils is called palaeontology

Options

A. B & D are correct
B. A, C & D are correct
C. All are incorrect
D. All are correct

Answer

To determine the correctness of the statements provided regarding fossils, we will analyze each statement step by step.

### Step-by-Step Solution:

1. **Statement A: "Fossils are remains of hard parts of life forms in Rock."**
- **Analysis:** This statement is accurate. Fossils primarily consist of the hard parts of organisms, such as bones, teeth, and shells, which become preserved in sedimentary rocks over time.
- **Conclusion:** This statement is **correct**.

2. **Statement B: "A study of fossils in different sedimentary layers indicates the geological period in which they live."**
- **Analysis:** This statement is also true. Fossils found in various sedimentary layers can provide information about the geological time periods during which the organisms existed, as different layers correspond to different ages.
- **Conclusion:** This statement is **correct**.

3. **Statement C: "Radio isotopes are often used to determine the age of the fossils."**
- **Analysis:** This statement is correct as well. Radioisotope dating methods, such as carbon dating, are commonly used to estimate the age of fossils and the rocks in which they are found.
- **Conclusion:** This statement is **correct**.

4. **Statement D: "Study of fossils is called palaeontology."**
- **Analysis:** This statement is accurate. The scientific study of fossils is indeed referred to as paleontology.
- **Conclusion:** This statement is **correct**.

### Final Conclusion:
Since all four statements (A, B, C, and D) have been analyzed and found to be correct, the final answer is that **all statements are correct**.

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