**Core Concept**
The question is testing the understanding of the calculation for the time it takes for an E-cylinder of anesthetic gas to empty, given a specific initial pressure and flow rate. This concept is crucial in anesthesia practice, where accurate estimation of gas supply is vital to ensure patient safety.

**Why the Correct Answer is Right**
To calculate the time it takes for the E-cylinder to empty, we use the formula: Time (minutes) = Total Volume (L) / Flow Rate (L/min). Since the E-cylinder is filled with 2,200 L of oxygen at 2,200 psig, and we are using 10 L/min, we need to calculate the volume of oxygen available at 500 psig. According to the Boyle's Law, at constant temperature, the volume of a gas is inversely proportional to the pressure. Therefore, at 500 psig, the volume of oxygen available is 2,200 L * (500 psig / 2,200 psig) = 500 L. Now, we can calculate the time it takes for the E-cylinder to empty: Time = 500 L / 10 L/min = 50 minutes.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided in the question.
**Option B:** This option is not provided in the question.
**Option C:** This option is not provided in the question.
**Option D:** This option is not provided in the question.

**Clinical Pearl / High-Yield Fact**
When administering anesthesia in a location without an oxygen supply line, it is essential to accurately estimate the time it takes for the E-cylinder to empty, to prevent running out of oxygen and compromising patient safety. Always calculate the available volume of oxygen using Boyle's Law and the initial pressure of the E-cylinder.

**Correct Answer:** C. 50 minutes.