Which of the following is not true?

Options

A. Ampicillin is not a natural antibiotic
B. Vancomycin is a broad spectrum antibiotic
C. Erythromycin is a bacteriostatic antibiotic
D. Prontosil is not converted into sulphanilamide in the body

Explanation

To determine which statement is not true among the given options, we will analyze each option one by one.

### Step-by-Step Solution:

1. **Analyze Option 1: "Amphicilin is not a natural antibiotic."**
- Amphicilin is indeed a synthetic antibiotic, which means it is man-made and not derived from natural sources.
- **Conclusion:** This statement is true.

2. **Analyze Option 2: "Benchomycin is a broad spectrum antibiotic."**
- Benchomycin is known to be effective against a wide range of bacteria, thus classifying it as a broad-spectrum antibiotic.
- **Conclusion:** This statement is also true.

3. **Analyze Option 3: "Erythromycin is a bacteriostatic antibiotic."**
- Erythromycin works by inhibiting bacterial growth rather than killing bacteria outright, which is characteristic of bacteriostatic antibiotics.
- **Conclusion:** This statement is true.

4. **Analyze Option 4: "Plantosil is not converted into Sulfanilamide in the body."**
- Plantosil is a prodrug that is converted into Sulfanilamide in the body. Therefore, the statement that it is not converted is incorrect.
- **Conclusion:** This statement is false.

### Final Answer:
The statement that is not true is **Option 4: "Plantosil is not converted into Sulfanilamide in the body."**