## **Core Concept**
The question tests understanding of the physiological response to trauma, specifically the mechanism of vasodilatation that occurs secondary to injury. This response is part of the body's acute reaction to trauma and involves various neural and chemical mediators.

## **Why the Correct Answer is Right**
The correct answer, **C. Substance P and Calcitonin Gene-Related Peptide (CGRP)**, is right because these neuropeptides are released from sensory nerve endings in response to trauma. Substance P and CGRP are known to cause vasodilatation, which is a key component of the neurogenic inflammatory response. This response leads to increased blood flow to the injured area, contributing to the signs of inflammation, such as redness and warmth.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because it does not specify the correct mediators involved in vasodilatation secondary to trauma.
- **Option B:** This option is incorrect as it does not accurately represent the substances responsible for the described physiological response.
- **Option D:** This option is incorrect because it does not identify the correct substances mediating vasodilatation in the context of trauma.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the release of substance P and CGRP from sensory nerve endings plays a significant role in the initiation of the inflammatory response following trauma. This highlights the importance of neurogenic factors in the mediation of inflammation, which is a critical aspect of the body's response to injury.

## **Correct Answer:** . Substance P and Calcitonin Gene-Related Peptide (CGRP)