**Core Concept**
The autonomic nervous system (ANS) is a branch of the peripheral nervous system that regulates involuntary functions, including heart rate, digestion, and blood pressure. The ANS has two main divisions: the sympathetic nervous system and the parasympathetic nervous system, which have distinct neurotransmitters that facilitate communication between neurons.

**Why the Correct Answer is Right**
The correct neurotransmitter in autonomic ganglia is **acetylcholine (ACh)**. ACh is released from the presynaptic neuron in the ganglion and binds to nicotinic acetylcholine receptors on the postsynaptic neuron, facilitating the transmission of signals to the effector organ. This is a critical step in the activation of the autonomic nervous system, allowing it to regulate various physiological processes.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the autonomic ganglia.
**Option B:** Dopamine is a neurotransmitter involved in reward processing, motor control, and other functions, but it is not the primary neurotransmitter in autonomic ganglia.
**Option C:** This option is not a valid neurotransmitter.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that acetylcholine is the primary neurotransmitter in autonomic ganglia, and its role in facilitating signal transmission is critical for the proper functioning of the autonomic nervous system.

**Correct Answer:** C. Acetylcholine.