**Core Concept**
Thyrotropin-releasing hormone (TRH) is a tripeptide hormone produced by the hypothalamus that plays a crucial role in regulating the secretion of thyroid-stimulating hormone (TSH) and prolactin. TRH acts on the anterior pituitary gland to stimulate the secretion of these two hormones, thereby influencing thyroid function and lactation.

**Why the Correct Answer is Right**
TRH binds to its receptors on the surface of thyrotrophs in the anterior pituitary, leading to the activation of adenylate cyclase and an increase in intracellular cyclic AMP (cAMP) levels. This results in the stimulation of TSH secretion, which in turn regulates the production of thyroid hormones by the thyroid gland. Additionally, TRH also stimulates the secretion of prolactin, a hormone involved in lactation and milk production. The dual effect of TRH on TSH and prolactin secretion highlights its importance in the regulation of both thyroid function and lactation.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because TRH does not solely stimulate the secretion of prolactin. While TRH does have a stimulatory effect on prolactin secretion, it also stimulates TSH secretion, making option C the correct answer.
**Option B:** This option is incorrect because TRH does not solely stimulate the secretion of TSH. While TRH is the primary stimulus for TSH secretion, it also stimulates the secretion of prolactin, making option C the correct answer.
**Option D:** This option is incorrect because TRH does stimulate the secretion of both TSH and prolactin, making option C the correct answer.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that TRH has a dual effect on the anterior pituitary gland, stimulating the secretion of both TSH and prolactin. This is a critical concept in understanding the regulation of thyroid function and lactation.

**✓ Correct Answer: C. Both**