During favorable conditions bacteria mainly reproduce by
(a) Budding
(b) Fragmentation
(c) Sporulation
(d) Fission

Options

A. Budding
B. Fragmentation
C. Sporulation
D. Fission

Answer

To solve the question "During favorable conditions bacteria mainly reproduce by," we need to analyze the options provided and understand the reproduction methods of bacteria.

### Step-by-Step Solution:

1. **Understanding Bacterial Reproduction**:
- Bacteria are prokaryotic organisms, meaning they lack a true nucleus and have their genetic material in the form of a nucleoid.

2. **Evaluating the Options**:
- **(a) Budding**: This is a form of asexual reproduction where a new organism develops from an outgrowth or bud on the parent organism. This method is more common in yeast and some multicellular organisms, not typically in bacteria.
- **(b) Fragmentation**: This is a method of asexual reproduction where an organism breaks into fragments, and each fragment can grow into a new organism. This is not a common method for bacteria.
- **(c) Sporulation**: This is a process where organisms produce spores, which can survive harsh conditions. While some bacteria can sporulate, it is not the primary method of reproduction during favorable conditions.
- **(d) Fission**: This refers to binary fission, a process where a single bacterial cell divides into two identical daughter cells. This is the most common method of reproduction in bacteria, especially under favorable conditions.

3. **Conclusion**:
- Based on the evaluation, the correct answer is **(d) Fission**, specifically binary fission, which is the primary mode of reproduction for bacteria during favorable conditions.

### Final Answer:
**(d) Fission**

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