**Core Concept**
Visceral noxious stimuli refer to painful sensations originating from the internal organs. The transmission of these stimuli involves the activation of nociceptors, which are specialized sensory neurons that respond to painful stimuli.

**Why the Correct Answer is Right**
Visceral noxious stimuli are mediated by the activation of nociceptors, specifically those expressing the transient receptor potential vanilloid 1 (TRPV1) receptor. These receptors are activated by the release of chemical mediators such as bradykinin and prostaglandins, which are produced in response to tissue injury. The activation of TRPV1 receptors leads to the generation of action potentials in nociceptors, which are then transmitted to the spinal cord and ultimately to the brain, where the pain is perceived.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it refers to somatic noxious stimuli, which are mediated by a different population of nociceptors that respond to mechanical and thermal stimuli.

**Option B:** This option is incorrect because it refers to the dorsal horn of the spinal cord, which is involved in the processing and modulation of pain, but is not the primary site of mediation for visceral noxious stimuli.

**Option C:** This option is incorrect because it refers to the release of neurotransmitters, which is a downstream event in the pain transmission pathway, but is not the primary mechanism of mediation for visceral noxious stimuli.

**Clinical Pearl / High-Yield Fact**
It's worth noting that the activation of TRPV1 receptors is also involved in the sensation of temperature and inflammation, making them a key target for the development of analgesic and anti-inflammatory therapies.

**Correct Answer: A. Somatic noxious stimuli.