Assertion : If the species-area relationship are analysed among very large areas like the entire continents, the value of Z, i.e., slope of line in the range of 0.1 to 0.2.
Reason : The value of Z, i.e., slope of line of species area relationship lies in the range of 0.6 to 1.2 when analysis is done among small areas.

Options

A. a) If both assertion and reason are true and reason is the correct explanation of assertion.
B. b) If both assertion and reason are true but reason is not the correct explanation of assertion.
C. c) If assertion is true but reason is false.
D. d) If both assertion and reason are false.

Explanation

To solve the question, we need to analyze the assertion and reason provided regarding the species-area relationship.

### Step-by-Step Solution:

1. **Understanding the Species-Area Relationship**:
- The species-area relationship is a concept that describes how the number of species (species richness) in a given area relates to the size of that area. This relationship is often represented mathematically as:
\[ \log S = \log C + Z \cdot \log A \]
where \( S \) is the number of species, \( A \) is the area, \( C \) is a constant, and \( Z \) is the slope of the line.

2. **Analyzing the Assertion**:
- The assertion states that for very large areas (like entire continents), the value of \( Z \) is between 0.1 to 0.2.
- This statement is incorrect. In reality, when analyzing large areas, the value of \( Z \) typically ranges from 0.6 to 1.2.

3. **Analyzing the Reason**:
- The reason states that for small areas, the value of \( Z \) lies in the range of 0.6 to 1.2.
- This statement is also incorrect. For small areas, the value of \( Z \) usually ranges from 0.1 to 0.2.

4. **Conclusion**:
- Both the assertion and the reason are false. Therefore, the correct answer to the question is that both the assertion and the reason are false.

### Final Answer:
The correct option is D: Both assertion and reason are false.

---