A : Majority of bacteria are autotrophs.
R : Chemoheterotrophic nutrition is absent in bacteria.

Options

A. If both assertion & reason are true and the reason is the correct explanation of the assertion
B. If both assertion & reason are true but the reason is not the correct explanation of the assertion
C. If assertion is true statement but reason is false
D. If both assertion and reason are false statements

Answer

To solve the assertion and reason question, we will analyze both statements step by step.

### Step 1: Analyze the Assertion
The assertion states: "Majority of bacteria are autotrophs."

- **Understanding Autotrophs**: Autotrophs are organisms that can produce their own food from inorganic substances. In the context of bacteria, there are indeed autotrophic bacteria, such as cyanobacteria, which can perform photosynthesis.
- **Understanding Bacterial Diversity**: However, bacteria are incredibly diverse and include both autotrophs and heterotrophs. Heterotrophic bacteria obtain their nutrients from organic compounds, and they are quite prevalent in various environments.

**Conclusion for Assertion**: The assertion is misleading because it implies that most bacteria are autotrophs, which is not accurate. Many bacteria are heterotrophic.

### Step 2: Analyze the Reason
The reason states: "Chemoheterotrophic nutrition is absent in bacteria."

- **Understanding Chemoheterotrophs**: Chemoheterotrophs are organisms that obtain energy by oxidizing organic compounds and also require organic compounds for their carbon needs. Many bacteria fall into this category, as they can utilize organic material for both energy and carbon.
- **Presence of Chemoheterotrophs**: In fact, chemoheterotrophic bacteria are very common and play essential roles in ecosystems, such as decomposing organic matter.

**Conclusion for Reason**: The reason is also incorrect because chemoheterotrophic nutrition is indeed present in many bacteria.

### Final Conclusion
Since both the assertion and the reason are false, we conclude that:

- **Assertion (A)**: False
- **Reason (R)**: False

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