Which neurotransmitter is released at the end of sympathetic nerve fibres?

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the specific neurotransmitter released at the end of sympathetic nerve fibers.

2. **Identifying Sympathetic Nerve Fibers**: Recognize that sympathetic nerve fibers are part of the autonomic nervous system and are responsible for the body's 'fight or flight' response during stressful situations.

3. **Role of Neurotransmitters**: Understand that neurotransmitters are chemical messengers that transmit signals across synapses from one neuron to another or to target cells.

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