## **Core Concept**
The question pertains to the disinfection of a flexible bronchoscope, which is a medical instrument used for visually examining the airways. Given that the instrument is used in a procedure room and needs to be made safe for the next patient, the focus is on appropriate disinfection methods to prevent cross-contamination.

## **Why the Correct Answer is Right**
The correct answer involves **high-level disinfection** or **sterilization** methods suitable for heat-sensitive equipment like flexible bronchoscopes. Among the provided options, **glutaraldehyde** (option C) is a high-level disinfectant commonly used for cleaning heat-sensitive endoscopes, including bronchoscopes. It effectively kills bacteria, viruses, and fungi, making it suitable for preparing the instrument for the next patient. This method is widely accepted in medical practice for such instruments.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because **autoclaving** (sterilization with high-pressure steam) is not suitable for heat-sensitive equipment like flexible bronchoscopes.
- **Option B:** This option is incorrect as **70% alcohol** is not considered sufficient for high-level disinfection required for instruments that come into contact with mucous membranes or non-intact skin.
- **Option D:** This option is incorrect because **formalin** is not typically used for the disinfection of medical instruments like bronchoscopes due to its toxicity and less effective spectrum against certain pathogens.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **glutaraldehyde** is a potent disinfectant used for **high-level disinfection** of medical instruments that are heat-sensitive. Its use requires careful handling and adequate rinsing to prevent any adverse reactions in patients.

## **Correct Answer:** . Glutaraldehyde.