**Core Concept**
The hypothalamus plays a crucial role in regulating various physiological processes, including hormone synthesis and storage. It is a key component of the hypothalamic-pituitary axis, which controls the endocrine system's response to stress, growth, and development.

**Why the Correct Answer is Right**
Oxytocin is a peptide hormone synthesized and stored in the hypothalamus. It is produced by the magnocellular neurons of the paraventricular and supraoptic nuclei. Oxytocin is released from the posterior pituitary gland and plays a vital role in social bonding, childbirth, and milk letdown during lactation. The hypothalamic neurons that produce oxytocin are responsible for regulating its release in response to various stimuli, including social interaction and childbirth.

**Why Each Wrong Option is Incorrect**
**Option A:** Vasopressin, also known as antidiuretic hormone (ADH), is synthesized in the hypothalamus but primarily stored in the posterior pituitary gland. While it is also a hormone involved in the regulation of water balance, it is not the correct answer in this context.
**Option B:** Adrenocorticotropic hormone (ACTH) is synthesized in the anterior pituitary gland, not the hypothalamus. It is released in response to corticotropin-releasing hormone (CRH) from the hypothalamus, but it is not stored in the hypothalamus.
**Option C:** Growth hormone-releasing hormone (GHRH) is synthesized in the hypothalamus but is not stored in the hypothalamus. Instead, it is released from the hypothalamus and acts on the anterior pituitary gland to stimulate the release of growth hormone.

**Clinical Pearl / High-Yield Fact**
Remember that oxytocin is often referred to as the "cuddle hormone" due to its role in social bonding and attachment. This hormone plays a crucial role in the development of maternal-infant bonding and is also involved in social recognition and memory.

**Correct Answer: C. Oxytocin**