Assertion : Tendons are very tough and inelastic.
Reason: Tendons join the muscles to the bone.

Options

A. If both Assertion and Reason are true but Reason is not a correct explanation of Assertion
B. If both Assertion and Reason are true but Reason is not a correct explanation of Assertion.
C. If Assertion is true but Reason is False
D. If both Assertion and Reason are false

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that "Tendons are very tough and inelastic." This means that tendons have a strong structure and do not stretch easily.

2. **Understanding the Reason**: The reason provided is "Tendons join the muscles to the bone." This indicates the primary function of tendons in the body.

3. **Evaluating the Assertion**: Tendons are indeed tough and inelastic. This toughness is necessary to withstand the forces exerted by muscles during movement without stretching, which helps in efficient energy transfer.

4. **Evaluating the Reason**: The reason is also true. Tendons serve the important function of connecting muscles to bones, allowing for movement when muscles contract.

5. **Determining the Relationship**: While both the assertion and the reason are true, the reason does not explain why tendons are tough and inelastic. The toughness and inelasticity of tendons are primarily due to their composition (collagen fibers) and their role in energy conservation during muscle contractions, rather than just their function of connecting muscles to bones.

6. **Conclusion**: Since both statements are true but the reason does not adequately explain the assertion, the correct answer is that both the assertion and reason are true, but the reason is not the correct explanation of the assertion.

### Final Answer:
Both assertion and reason are true, but the reason is not the correct explanation of the assertion.