**Core Concept**
The question tests knowledge of amino acid metabolism, specifically the synthesis of important biomolecules from essential amino acids. Essential amino acids cannot be synthesized by the human body and must be obtained through the diet.

**Why the Correct Answer is Right**
The correct answer is related to the synthesis of neurotransmitters, where an essential amino acid is a precursor. For instance, tryptophan, an essential amino acid, is a precursor to serotonin, a key neurotransmitter.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it is not directly synthesized from an essential amino acid.
**Option B:** Incorrect as it is not the primary example of a molecule synthesized from an essential amino acid.
**Option C:** Incorrect because its synthesis does not primarily involve an essential amino acid.

**Clinical Pearl / High-Yield Fact**
Remember that tryptophan is an essential amino acid and a precursor to serotonin, a crucial neurotransmitter involved in mood regulation.

**Correct Answer:** D. Nitric oxide is synthesized from arginine, but more directly, serotonin is synthesized from tryptophan, an essential amino acid. **Correct Answer: D.**