**Core Concept**
The question tests the understanding of how amino acids in the diet influence nitrogen balance and the role of insulin in this process. Amino acids are the building blocks of proteins and play a crucial role in maintaining nitrogen balance in the body, especially in seriously ill patients. The correct answer relates to the physiological mechanism by which insulin affects amino acid metabolism.

**Why the Correct Answer is Right**
The addition of amino acids in the diet results in a positive nitrogen balance due to the increased secretion of insulin. Insulin has anabolic effects, stimulating protein synthesis and inhibiting protein breakdown. When insulin levels rise in response to amino acids, it promotes the uptake of glucose and amino acids by cells, which in turn stimulates protein synthesis. This results in a net positive nitrogen balance. The anabolic effects of insulin are mediated through the activation of key enzymes involved in protein synthesis, such as protein kinase B (Akt) and the mTOR pathway.

**Why Each Wrong Option is Incorrect**
**Option A:** Increased growth hormone secretion would have the opposite effect, promoting protein breakdown and a negative nitrogen balance.

**Option B:** Enhanced rate of gluconeogenesis would also have a negative effect on nitrogen balance, as it would lead to the breakdown of amino acids to produce glucose.

**Option C:** Increased absorption of amino acids from the diet is a necessary step, but it is not the primary mechanism by which amino acids influence nitrogen balance.

**Clinical Pearl / High-Yield Fact**
In critically ill patients, the anabolic effects of insulin can be leveraged to promote positive nitrogen balance and support wound healing. This is achieved through insulin therapy, which aims to maintain normoglycemia while promoting anabolic effects.

**Correct Answer Line**
✓ Correct Answer: D. Increased secretion of Insulin