**Core Concept**
The Venturi mask is a type of oxygen delivery device used in anesthesia and critical care to provide a precise concentration of oxygen to the patient. It works on the principle of creating a pressure gradient to mix oxygen with room air, thereby achieving a specific FiO2 (fraction of inspired oxygen) concentration.

**Why the Correct Answer is Right**
The Venturi mask uses a specific jet size and a conical orifice to create a pressure gradient, which mixes oxygen with room air. The jet size determines the pressure gradient, and consequently, the FiO2 concentration. A Venturi mask with a specific jet size can achieve a maximum FiO2 concentration of 60%. This is because the pressure gradient created by the jet size is sufficient to mix oxygen with room air up to a maximum concentration of 60%. The Venturi mask is designed to provide a precise and consistent FiO2 concentration, making it an essential tool in anesthesia and critical care.

**Why Each Wrong Option is Incorrect**
**Option A:** 90% is incorrect because the Venturi mask is not capable of achieving such a high FiO2 concentration. The pressure gradient created by the jet size is not sufficient to mix oxygen with room air to achieve a concentration of 90%.
**Option B:** 100% is incorrect because the Venturi mask is designed to mix oxygen with room air, and it is not possible to achieve 100% FiO2 concentration using this device.
**Option D:** 80% is incorrect because the Venturi mask is not capable of achieving such a high FiO2 concentration. While some Venturi masks may be able to achieve higher concentrations, the maximum concentration is 60%.

**Clinical Pearl / High-Yield Fact**
When using a Venturi mask, it's essential to ensure that the correct jet size is used to achieve the desired FiO2 concentration. Using the wrong jet size can lead to inaccurate FiO2 concentrations, which can have serious consequences for the patient.

**Correct Answer:**
✓ Correct Answer: C. 60%