**Core Concept**
The question tests the understanding of **serotonergic receptors** and their role in neurotransmission, specifically focusing on **autoreceptors** that regulate the release of **serotonin**.

**Why the Correct Answer is Right**
The correct answer is related to the **5-HT1A receptor**, which is known to act as an **autoreceptor** on the soma and dendrites of **serotonergic neurons**, regulating the firing rate and thus the release of **serotonin**. This receptor is involved in a negative feedback mechanism, reducing **serotonin** release when activated.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it does not specifically refer to a known autoreceptor function among serotonergic receptors.
**Option B:** Incorrect as it is not directly associated with the autoreceptor function in serotonergic neurotransmission.
**Option D:** Incorrect because, while involved in serotonergic transmission, it does not primarily function as an autoreceptor.

**Clinical Pearl / High-Yield Fact**
Remember that **5-HT1A receptors** play a crucial role in the regulation of mood, and their autoreceptor function is key to understanding the mechanism of action of certain **antidepressants**.

**Correct Answer:** D. 5-HT1A.