Okay, let's tackle this question about the net protein utilization (NPU) of egg. First, I need to recall what NPU means. Net protein utilization is a measure of how efficiently the body uses dietary protein. It's calculated by taking the amount of nitrogen retained in the body divided by the amount of nitrogen ingested, then multiplied by 100 to get a percentage. So, the higher the NPU, the better the protein source.

Egg protein is considered a high-quality protein because it has all the essential amino acids and is easily digestible. I remember that egg has one of the highest NPU values, maybe around 95-100%. Let me think, the NPU of egg is often cited as 95%, but sometimes sources say 100%. Wait, maybe it's because the digestibility is almost 100%, and the biological value is also high. The NPU takes into account both digestibility and the body's ability to retain the nitrogen. So if the digestibility is 100% and the retention is also high, the NPU would be high.

Now, looking at other options. Let's say the options were for different proteins. For example, milk might have an NPU around 85%, soy around 70%, and wheat around 50%. But the question here is about egg. So the correct answer should be the highest, which is 95% or 100%. But I need to check exact values. Some sources say egg's NPU is 95%, others say 100%. Wait, maybe the NPU is calculated as (retained nitrogen / ingested nitrogen) * 100. If egg has 100% digestibility and high retention, maybe the NPU is 100%. However, in some references, the NPU of egg is listed as 95%. Hmm, I need to be precise here.

Clinical pearl: Egg is a reference protein with high NPU, making it excellent for dietary needs. Remember that NPU combines digestibility and biological value. So if the options include 95%, that's likely correct. The key is to know that egg has one of the highest NPUs, so the answer is 95% or 100%, depending on the exact calculation method used in the source. But in most standard references, egg's NPU is 95%. Therefore, the correct answer should be 95%.

**Core Concept**
Net Protein Utilization (NPU) measures the proportion of ingested dietary nitrogen that is retained in the body, reflecting both digestibility and metabolic efficiency. Egg protein is a **high-quality protein** with near-complete amino acid profile and high digestibility.

**Why the Correct Answer is Right**
Egg protein has an NPU of approximately **95%**, meaning 95% of ingested nitrogen is retained for tissue synthesis. This high value stems from its **complete essential amino acid composition**, **>90% digestibility**, and minimal nitrogen loss in feces/urine. The liver efficiently converts absorbed amino acids into albumin and other proteins, with minimal catabolism.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect if it implies lower NPU (e.g., 70–

✓ Correct Answer: A. 96