**Core Concept**
Diffusion hypoxia is a complication associated with nitrous oxide (N2O) anesthesia, which occurs when N2O is rapidly discontinued. This leads to a decrease in oxygen concentration in the lungs, causing a temporary reduction in oxygen delivery to the tissues. The underlying principle being tested is the management of N2O anesthesia to prevent this complication.

**Why the Correct Answer is Right**
To minimize the effects of diffusion hypoxia, patients should be oxygenated for at least 5 minutes after discontinuation of N2O-O2 analgesia. This allows the N2O to be eliminated from the bloodstream and prevents a rapid decrease in oxygen concentration. The administration of supplemental oxygen helps to maintain adequate oxygenation of the tissues and prevents the development of diffusion hypoxia.

**Why Each Wrong Option is Incorrect**
**Option A:** Oxygenation for 1 minute is insufficient to prevent diffusion hypoxia, as it does not allow sufficient time for the elimination of N2O from the bloodstream.
**Option B:** The use of 100% oxygen is not necessary, as the goal is to maintain adequate oxygenation, not to provide a high concentration of oxygen.
**Option C:** The duration of oxygenation is not specified, making this option vague and incorrect.

**Clinical Pearl / High-Yield Fact**
A mnemonic to remember is "O2 for 5" to ensure adequate oxygenation after discontinuation of N2O-O2 analgesia.

**Correct Answer:** D.