The most commonly used bioreactor is of stirring type. The stirrer facilitates

Options

A. Temperature control
B. pH control
C. Oxygen availability
D. Product removal

Answer

### Step-by-Step Solution

1. **Understanding the Question**: The question asks about the role of a stirrer in a stirring type bioreactor, which is the most commonly used type of bioreactor.

2. **Defining a Stirred Tank Bioreactor**: A stirred tank bioreactor is a cylindrical vessel designed for the cultivation of biological agents such as cells, enzymes, and antibodies on a large scale. It is commonly used in industrial settings for bioprocessing.

3. **Function of the Stirrer**: The stirrer in a stirred tank bioreactor serves several purposes:
- It ensures even mixing of the contents within the bioreactor.
- It helps maintain uniform conditions throughout the reactor, which is crucial for the growth and productivity of the biological agents.

4. **Evaluating the Options**:
- **Option 1: Temperature Control**: The stirrer does not primarily facilitate temperature control.
- **Option 2: pH Control**: The stirrer does not directly facilitate pH control.
- **Option 3: Oxygen Availability**: The stirrer plays a significant role in ensuring that oxygen is evenly distributed throughout the bioreactor, which is essential for aerobic processes.
- **Option 4: Product Removal**: The stirrer does not facilitate product removal.

5. **Conclusion**: Based on the evaluation of the options, the correct answer is that the stirrer facilitates **oxygen availability** in the stirred tank bioreactor.

### Final Answer
The stirrer facilitates **oxygen availability** in the stirred tank bioreactor.

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