Long and generally unbranched extension of a neuron.

Explanation

### Step-by-Step Solution:

1. **Understanding the Neuron**: The neuron is the basic structural and functional unit of the nervous system. It is specialized for transmitting information throughout the body.

2. **Identifying Neuron Components**: Neurons have various parts, including the cell body, dendrites, and axons. Dendrites are branched extensions that receive signals from other neurons, while axons are long and generally unbranched extensions.

3. **Function of Dendrites and Axons**:
- Dendrites bring information to the cell body from other neurons.
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