## **Core Concept**
The hot air oven is a commonly used method for sterilization in medical and laboratory settings. It works by using high temperatures to kill microorganisms. The process involves heating the oven to a specific temperature and holding it at that temperature for a certain period to ensure that all microorganisms are eliminated.

## **Why the Correct Answer is Right**
The correct holding time for a hot air oven at 160°C is 45 minutes (or 1 hour at 160°C in some protocols, but 45 minutes is a commonly accepted duration). This duration ensures that the heat penetrates through the materials being sterilized and effectively kills all forms of microbial life. The temperature and time are critical because they directly influence the lethality of the sterilization process.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because it does not specify a duration that aligns with standard sterilization protocols for hot air ovens at 160°C.
- **Option B:** This option is incorrect for similar reasons; the specified time does not match established guidelines for effective sterilization at the given temperature.
- **Option D:** This option suggests a longer duration, which, while it might ensure sterilization, is not the minimum accepted time for effective sterilization at 160°C.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the effectiveness of sterilization by hot air oven depends on both the temperature and the duration. For example, at 160°C, a holding time of 45 minutes is generally recommended. However, if the temperature is lowered to 150°C, the holding time typically needs to be extended to 150 minutes. This highlights the importance of following precise protocols for sterilization.

## **Correct Answer:** C. 45 minutes.