**Core Concept**
Galactorrhea is a condition characterized by the spontaneous flow of milk from the breast, not associated with childbirth or lactation. It can be caused by various factors, including hormonal imbalances and certain medications. In this context, the question is testing the student's knowledge of medications that can induce galactorrhea.

**Why the Correct Answer is Right**
Pyridoxine, also known as vitamin B6, is not typically associated with galactorrhea. The other options, however, are known to cause galactorrhea as a side effect. Methyldopa, a centrally acting antihypertensive agent, can stimulate prolactin release, leading to galactorrhea. Tricyclic antidepressants, particularly those with significant anticholinergic properties, can also cause galactorrhea by inhibiting dopamine release, which normally suppresses prolactin secretion. Phenothiazines, a class of antipsychotic medications, are well-documented to cause hyperprolactinemia and subsequent galactorrhea due to their dopamine antagonist activity.

**Why Each Wrong Option is Incorrect**
**Option A:** Methyldopa is a known cause of galactorrhea, so this option is incorrect.
**Option B:** Tricyclic antidepressants can also cause galactorrhea, making this option incorrect as well.
**Option D:** Phenothiazines are a well-established cause of galactorrhea, making this option incorrect.

**Clinical Pearl / High-Yield Fact**
When considering medications that may cause galactorrhea, remember the "dopamine antagonist" mechanism, which can lead to increased prolactin levels and subsequent galactorrhea. This is particularly relevant in patients taking antipsychotic medications, antidepressants with significant anticholinergic properties, and centrally acting antihypertensive agents like methyldopa.

**✓ Correct Answer: C. Pyridoxine**