Synthetic tranquillisers are mostly barbituric acid derivatives (e.g. veronal, luminal, seconal, amytal and nembutal). Other tranquillisers which are not barbituric acid derivatives are chlordiazepoxide, equanil meprobamate, valium (diazepam), etc. Opium alkaloids such as morphine and codeine are powerful analgesics (reduce pain). Heroin which is morphine diacetate is a widely used narcotic analgesic. Drugs which are used to cure diseases caused by microbes are called antimicrobials. These may be either sulpha drugs such as sulphapyridine, sulphadiazine, sulphaguanidine or they may be antibiotics. Antibiotics such as erythromycin, tetracycline, chloramphenicol which inhibit or arrest the growth of microbes are called bacteriostatic while others which kill the microbes are called bactericidal antibiotics.
Which of the following is/are antibacterials ?

Options

A. Penicillin
B. Sulphapyridine
C. Ofloxacin
D. All

Answer

To determine which of the given options are antibacterials, we need to analyze the information provided in the question and the video transcript regarding different types of drugs.

### Step-by-Step Solution:

1. **Understanding Antimicrobials**:
- Antimicrobials are drugs used to treat infections caused by microbes. They can be classified into two categories: sulpha drugs and antibiotics.

2. **Identifying Sulpha Drugs**:
- The transcript mentions sulpha drugs such as sulphapyridine, sulphadiazine, and sulphaguanidine. These are known to have antibacterial properties.

3. **Identifying Antibiotics**:
- The transcript also lists antibiotics like erythromycin, tetracycline, and chloramphenicol. These antibiotics can be further classified into:
- **Bacteriostatic**: Inhibit the growth of bacteria (e.g., erythromycin, tetracycline).
- **Bactericidal**: Kill bacteria (e.g., penicillin).

4. **Evaluating the Options**:
- The question asks which of the following is/are antibacterials. The options provided in the video include penicillin, sulphapyridine, and another antibiotic (ophthalexin).
- Since all these drugs are known to have antibacterial effects, we can conclude that they are indeed antibacterials.

5. **Final Conclusion**:
- Therefore, the correct answer is that all the mentioned drugs (penicillin, sulphapyridine, and ophthalexin) are antibacterials.

### Answer:
All of the mentioned options are antibacterials.