Food poisoning is caused by

Options

A. Clostridium botulinum
B. Salmonella typhi
C. Escherichia coli
D. Bacillus megatherium.

Answer

### Step-by-Step Solution:

1. **Understanding Food Poisoning**: Food poisoning is a condition that occurs when a person ingests food contaminated with harmful bacteria, viruses, or toxins. It can lead to various symptoms such as nausea, vomiting, diarrhea, and abdominal pain.

2. **Identifying the Bacteria**: The question presents four options of bacteria that could potentially cause food poisoning:
- Option 1: Clostridium botulinum
- Option 2: Salmonella typhi
- Option 3: Escherichia coli
- Option 4: Bacillus megaterium

3. **Analyzing Each Option**:
- **Clostridium botulinum**: This is an anaerobic, spore-forming bacillus known for producing a potent neurotoxin called botulinum toxin. When ingested, it can lead to a severe form of food poisoning known as botulism, which can be fatal. Therefore, this is a strong candidate for causing food poisoning.

- **Salmonella typhi**: This bacterium causes typhoid fever, not food poisoning. It is a gram-negative, non-spore-forming bacillus. Thus, this option is incorrect.

- **Escherichia coli**: While some strains of E. coli can cause food poisoning, most strains are harmless and reside in the intestines of warm-blooded organisms. Therefore, it is not the primary cause of food poisoning in this context.

- **Bacillus megaterium**: This is a large, gram-positive, aerobic spore-forming bacillus. It is not known to cause food poisoning and is more recognized for its potential use in biocontrol against plant diseases.

4. **Conclusion**: After analyzing all the options, the bacteria that is primarily responsible for food poisoning is **Clostridium botulinum**. It produces a neurotoxin that can lead to severe illness when contaminated food is consumed.

### Final Answer:
Food poisoning is caused by **Clostridium botulinum**.

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