**Core Concept**
Prolactin-releasing factors (PRFs) are substances that stimulate the secretion of prolactin from the anterior pituitary gland. The regulation of prolactin secretion is a complex process involving various neurotransmitters and hormones.

**Why the Correct Answer is Right**
Prolactin secretion is primarily regulated by the hypothalamic-pituitary axis. The main prolactin-releasing factors include dopamine's antagonist, which is thyrotropin-releasing hormone (TRH), and vasoactive intestinal peptide (VIP). TRH stimulates the secretion of prolactin from the anterior pituitary gland, while VIP has a synergistic effect. The correct answer will be a factor that does not stimulate prolactin secretion.

**Why Each Wrong Option is Incorrect**
**Option A:** TRH is a known prolactin-releasing factor, so this option is incorrect.
**Option B:** VIP is a synergistic factor that enhances prolactin secretion, making this option incorrect.
**Option C:** Galanin is a neuropeptide that stimulates prolactin secretion, so this option is incorrect.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that dopamine has an inhibitory effect on prolactin secretion, acting as a prolactin-inhibiting factor. This is a classic exam trap, as students often overlook dopamine's role in prolactin regulation.

**Correct Answer: C. Galanin**