**Core Concept**
The question is testing the decarboxylation of amino acids to produce biogenic amines with vasodilatory properties. This process involves the removal of a carboxyl group (-COOH) from the amino acid, resulting in the formation of a new compound with distinct physiological effects.

**Why the Correct Answer is Right**
The correct answer is **Histidine**, which upon decarboxylation produces **Histamine**. Histamine is a potent vasodilator that plays a crucial role in various physiological processes, including allergic reactions, immune responses, and smooth muscle contraction. The decarboxylation reaction is catalyzed by the enzyme histidine decarboxylase, which breaks down the carboxyl group of histidine to form histamine.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because **Glutamate** decarboxylation produces **GABA** (gamma-aminobutyric acid), an inhibitory neurotransmitter, not a vasodilator.
* **Option B:** This option is incorrect because **Phenylalanine** decarboxylation produces **Tyramine**, a vasoconstrictor, not a vasodilator.
* **Option D:** This option is incorrect because **Tryptophan** decarboxylation produces **Serotonin**, a neurotransmitter involved in mood regulation, appetite, and sleep, but not a direct vasodilator.

**Clinical Pearl / High-Yield Fact**
The biogenic amine hypothesis of schizophrenia suggests that an imbalance of neurotransmitters such as histamine, dopamine, and serotonin may contribute to the development of the disorder. This highlights the importance of histamine in neurological and psychiatric conditions.

**Correct Answer:** C.