Bacteria were first discovered by :

Options

A. Robert Koch
B. A. V. Leeuwenhoek
C. Louis Pasteur
D. Robert Hooke

Explanation

**Step-by-Step Solution:**

1. **Understanding Bacteria**: Bacteria are small, single-celled organisms that are classified as prokaryotes. This means they do not have a nucleus or other membrane-bound organelles.

2. **Historical Context**: The question asks about the discovery of bacteria, which refers to the first observation of these organisms by a scientist.

3. **Identifying the Scientist**: The first person to observe bacteria was Antonie van Leeuwenhoek, a Dutch scientist.

4. **Significance of Discovery**: Leeuwenhoek is often referred to as the "father of microbiology" due to his pioneering work in observing microscopic life.

5. **Method of Observation**: In 1676, Leeuwenhoek used a single-lens microscope, which he crafted himself, to closely examine water samples. This led to the discovery of tiny organisms, which we now know as bacteria.

6. **Conclusion**: Therefore, the answer to the question is that bacteria were first discovered by Antonie van Leeuwenhoek.

**Final Answer**: Bacteria were first discovered by Antonie van Leeuwenhoek.

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