[A]: Decrease in mortality would result in de- creased population growth rate.
[R]: Mortality is the birth rate per thousand in- dividuals

Options

A. If both A and R are true and R is the correct explanation of A
B. If both A and R are true but R is not the correct explanation of A
C. If A is true and R is false
D. If both A and R are false

Answer

To solve the assertion-reason question, we need to analyze both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understand the Assertion**:
- The assertion states that "a decrease in mortality would result in decreased population growth rate."
- Mortality refers to the death rate in a population. If mortality decreases, it means fewer individuals are dying.

2. **Analyze the Implications of the Assertion**:
- If fewer individuals are dying, the population would likely grow faster, not slower. Therefore, the assertion is incorrect.

3. **Understand the Reason**:
- The reason states that "mortality is the birth rate per thousand individuals."
- This statement is fundamentally incorrect. Mortality refers to the death rate, while the birth rate is referred to as natality.

4. **Analyze the Implications of the Reason**:
- Since mortality is not defined as the birth rate, this reason is also incorrect.

5. **Conclusion**:
- Both the assertion and the reason are false.

### Final Answer:
- The correct option is that both the assertion and the reason are false.

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